Originally Published: 10 MAY 21 04:42 ET

Updated: 10 MAY 21 12:30 ET

By Hollie Silverman, CNN

(CNN) -- A gunman opened fire at a family birthday party in Colorado Springs on Sunday, leaving six people dead and a community in mourning.

There were at least nine mass shootings in the country over the weekend that combined left at least 15 people dead and 30 more wounded, according to CNN reporting and an analysis of data from Gun Violence Archive (GVA), local media and police reports.

CNN defines a mass shooting as incident with four or more people killed or wounded by gunfire -- excluding the shooter.

This weekend's shootings provide a glimpse into the rise in violence that began last year and that has continued ever since. Criminology experts have pointed to a perfect storm of factors, including economic collapse, Covid's severing of social connections and mistrust in police.

In the Colorado Springs shooting, the suspected gunman -- believed to be a boyfriend of one of the victims -- also died, police said.

"Words fall short to describe the tragedy that took place this morning," Colorado Springs Police Chief Vince Niski said in a statement. "From the officers who responded to the shooting to the investigators still on scene, we are all left incredibly shaken."

From a town house community and a neighborhood park, to a hotel and a nightclub, these are the mass shootings that shook communities across seven states.

Phoenix

An overnight shooting at the Hyatt Regency Hotel left one man dead and at least seven others wounded, Phoenix Police Sgt. Margaret Cox said at a news conference Sunday.

A group attending an event at the hotel got into an altercation that resulted in the gunfire, Cox said. All of the victims are believed to be between the ages of 18 and 22.

Cox told reporters there was more than one shooter, but investigators are trying to find exactly how many and what types of guns were used.

The shooting was an isolated incident and not a random act, she added.

Woodlawn, Maryland

Three people are dead and another was injured during a shooting at a town home Saturday morning just outside of Baltimore, authorities said.

Police responded to a call for an active shooter and fire scene at a town home community in the Woodlawn suburb, the Baltimore County Police Department said in a news release.

Investigators say the suspect lit his residence on fire and forced his way into his neighbors' home, where he then shot and stabbed them, according to the release. He shot two more neighbors as they came out of their home, including a 24-year-old who died, the release said.

The suspect was confronted by responding officers who ordered him drop his handgun, according to the release. He was then shot by officers and taken into custody after refusing, the release said, and later died in the hospital.

California

At least three people were killed and nine others injured in three separate shootings in California.

In Los Angeles, one person died and five others were injured in a shooting late Sunday.

Three people with gunshot injuries were taken to hospitals in critical condition and a fifth person who suffered a non-life-threatening injury was also transported, according to a media alert from the Los Angeles Fire Department (LAFD).

On Saturday, four people were injured in a shooting outside of a nightclub in Citrus Heights, police told CNN affiliate KCRA. Officers found several fights happening in the parking lot of the club and surrounding area, according to the affiliate.

That same night, more than 400 miles away in Compton, police were in the area when they heard shots fired.

Deputies found two men believed to be 15-20 years old dead at the scene, according to a news release from the Los Angeles County Sheriff's Department. Police were later alerted to two other people seeking treatment for gunshot wounds at a nearby hospital.

Newark, New Jersey

Four people were injured in a shooting in Newark on Sunday, according to a tweet from the police department.

Two men and two women "were injured by gunfire," according to the tweet.

Police are asking anyone with information to call 1-877-NWK-TIPS to provide tips.

Milwaukee

Authorities in Milwaukee are investigating a shooting that injured four people on Saturday afternoon, a news release from the Milwaukee Police Department said.

The victims, ages 23 to 45, all suffered non-life-threatening injuries, the release said.

Two men have been arrested in connection with the shooting and charges will be forwarded to the prosecutor's office in the coming days, according to the release.

St. Louis County, Missouri

Two people are dead and three others injured after a shooting in a park in Kinloch, on Friday night, St. Louis County Police said in a news release.

"It was all peaceful and beautiful and next thing you know ... gunfire just erupted," Willoid Williams, who witnessed the shooting, told CNN affiliate KMOV.

Williams said he was in the area for a "neighborhood celebration" when a truck pulled up and started shooting.

"It's just outrageous, it was crazy," Williams said.

Police said they did not find any victims when they arrived at the scene around 6:30 p.m., but later found that five people had taken themselves to the hospital.

Two of the men were pronounced dead at the hospital while the other victims suffered non-life-threatening injuries, according to the release.

The investigation is ongoing and police are asking anyone with information to call the St. Louis County Police Department.