By Jason Hanna and Madison Park, CNN

(CNN) -- A package that exploded early Tuesday at a FedEx sorting center near San Antonio was not the only parcel there that investigators believe contained an explosive device, San Antonio Police Chief Bill McManus said.

Tuesday's blast in Schertz, Texas -- which officials said injured one FedEx worker -- came as four explosions, two of them deadly, have rattled the city of Austin, about an hour's drive northeast of Schertz, since March 2. The latest developments, including the revelation of the second package and hundreds more reports of dubious parcels, added to a mounting anxiety that one official described as "absolute panic."

"There was one other package" besides the one that exploded Tuesday at the FedEx facility in Schertz "that we believe was also loaded with an explosive device," McManus said late Tuesday morning during a news conference. That second parcel was no longer at the facility, and authorities were "working on" it, he said.

A FedEx spokesman said, "the individual responsible also shipped a second package that has now been secured and turned over to law enforcement."

The company also turned over to law enforcement "extensive evidence related to these packages and the individual that shipped them collected from our advanced technology security systems," Jim McCluskey added in a statement Tuesday.

Timeline of the bombings

Meantime, an Austin police bomb squad had been called in to investigate a suspicious package at a FedEx facility near Austin-Bergstrom International Airport, Officer Destiny Wilson said early Tuesday afternoon. The report was among more than 1,200 calls about suspicious packages that had come in to Austin police since March 12, the agency said.

Wilson did not know of any link between the package and the Schertz explosion, she said.

Key developments

• The FBI is investigating a "confirmed link" between packages involved in the Austin investigations and a mail delivery office in Sunset Valley, southwest of Austin, police in Sunset Valley said Tuesday. They did not elaborate, or indicate which packages were connected to the Sunset Valley office.

• President Donald Trump did not comment when asked Tuesday if he thought the bombings were acts of domestic terrorism. "Terrible. The bombings in Austin are terrible," he said. "This is obviously a very very sick individual, or maybe individuals. These are sick people and we will get to the bottom of it. We will be very strong." Trump called the situation "absolutely disgraceful" and said of those responsible: "We have to find them really immediately."

• At the Schertz FedEx facility, a package that was moving along an automated conveyor exploded around 12:25 a.m. Tuesday, Schertz Police Chief Michael Hansen said during a news briefing Tuesday morning outside the building.

• A worker standing near the explosion complained of ringing in her ears, and was treated and released, Hansen said. However, McManus later said a worker was knocked off her feet and suffered a concussion.

• Based on preliminary information gathered at the scene, there could be a connection between the Shertz blast and the four Austin explosions, FBI San Antonio spokeswoman Michelle Lee said. "We suspect it is related to our investigation," Lee said.

• But FBI special agent James Smith said it was too early to know whether the Schertz blast was connected to any of the ones in Austin, which killed two people and injured four others over 17 days.

• If the FedEx explosion is confirmed to be linked to the Austin blasts, it would represent a new method for the bomber or bombers. None of the four previous explosives was mailed, police have said.

• Hansen, the Schertz police chief, said he was confident the package that exploded there was not meant to target that facility or the city, though he wouldn't say why.

• The FBI's Smith declined to answer reporters' questions about whether the package that blew up was destined for Austin. Smith also said he had no reason to believe people in Schertz face any threat.

• Reps. Sheila Jackson-Lee and Bob Goodlatte on Tuesday asked an FBI acting deputy director for a briefing on efforts to find the bombmaker. "There is absolute panic in Austin, and we need to be able to part of the understanding of the notice given to these citizens in Austin," said Jackson-Lee, who represents Houston. "There is absolute panic going on there now."

The four Austin bombings

In Austin, authorities have been combing for clues to the four explosions there, the first three of which involved cardboard packages that were left in front yards or porches and weren't delivered by the US Postal Service or services such as UPS or FedEx, police say.

Those first three explosions -- one on March 2, and two more on March 12 -- killed or wounded three African-American people and one Hispanic person after they encountered the packages. The explosions happened in east Austin areas that predominantly have minority residents, and some in the area expressed concerns that the attacks might have been racially motivated.

Police have not uncovered a motive and have not ruled out the possibility those bombings could be hate crimes.

In the fourth blast, a device on Sunday was triggered by a tripwire, injuring two white men, police said. That device had been left on the side of a road in an area where most residents are white. Those men are in good condition, still being treated at St. David's South Austin Medical Center, a hospital spokesperson said.

"The use of a tripwire is far less discriminating than leaving parcel bombs at residences and suggests that (Sunday's) victims were not specifically targeted," the global think tank Stratfor said in one of its Threat Lens reports.

If one perpetrator is behind the four Austin bombs and the device in Schertz, then the person deployed an unusually wide range of skills and delivery methods, CNN law enforcement analyst James Gagliano said.

"Some of these folks, ... as long as the bombmaker walks away with 10 fingers and 10 toes, that's successful to them," Gagliano, a retired FBI supervisory special agent, said.

"But the method, the delivery system and the different means that he's having these things in place shows that he's trying to show -- if it's the same person on all five of these -- a full panoply of different ways of doing this," he added, "and that's frightening."

Three members of the Congressional Black Caucus called Monday for federal officials to classify the bombings as terrorist attacks and determine whether they are "ideologically or racially motivated."

The NAACP called the incidents "acts of domestic terrorism" and called for vigilance and caution for communities in Austin.

What agencies are involved?

More than 350 special agents assigned by the FBI, as well as ATF agents and forensic investigators in Quantico, Virginia, are on the Austin case.

At the state level, about 100 Texas Department of Public Safety officers, sergeants, and special agents, as well as the Texas Ranger bomb squad, bomb-sniffing dogs, intelligence agents and helicopters are also involved, CNN affiliate KXAN reported.

Police departments in Houston and San Antonio are sending bomb technicians and canine teams to Austin, their police chiefs said Monday.

How are they examining the evidence?

ATF has taken evidence from the four blast sites in Austin, Police Chief Brian Manley said.

"The prior three scenes are already in the lab at Quantico, and the evidence from the scene from last night is on its way to Quantico as well," he told CNN's Anderson Cooper Monday night.

"They're looking at the devices, they're comparing them, looking for similarities," he said. "The similarities they've seen to this point, lead them to believe -- as we do -- that these are all being constructed by the same person or persons who are responsible for this."

How are they handling the tips?

Austin police has received lots of tips, Manley said Monday night.

"As each tip comes in, it gets assigned to either a team of FBI agents, ATF agents or Austin Police detectives to do follow-up work on," he said.

Manley urged residents to call police with any information.

"No matter how inconsequential you think it may be, that may be the piece of evidence we need to link it together and solve this before we have someone else in our community that gets seriously injured or killed," he said.

What resources are they getting?

Texas Gov. Greg Abbott announced more than $265,500 in emergency funding for the Austin Police Department and the Texas Ranger Response Team to purchase seven portable X-ray systems.

The systems can be used on site to quickly assess the safety of packages.

"I want to ensure everyone in the Austin region and the entire state that Texas is committed to providing every resource necessary to make sure these crimes are solved as quickly as possible," Abbott said in a statement.

The reward for information leading to the arrest of anyone responsible for the blasts totals $115,000.

What are police asking residents to do?

Police are appealing to residents to pay attention to their surroundings. Residents shouldn't approach or touch anything that looks suspicious, Manley said.

"We now need the community to have an extra level of vigilance and pay attention to any suspicious device -- whether it be a package or a bag, a backpack -- anything that looks out of place," Austin's police chief said Monday. "Do not approach items like that."

Authorities are also asking anyone in the neighborhood with security camera footage to call police.