Originally Published: 07 JUL 22 00:22 ET

By Kiely Westhoff and Aya Elamroussi, CNN

(CNN) -- One of the two police officers injured in a shooting during a July Fourth celebration in Philadelphia didn't realize he had been shot until he arrived at a hospital and found a bullet lodged in his hat, he told CNN.

Officer Sergio Diggs and deputy John Foster were both injured while providing security at a July Fourth concert on the Benjamin Franklin Parkway when shots were fired shortly before 10 p.m., just before fireworks went off, police said.

Diggs, 36, was walking to rejoin other officers after throwing an item in the trash when he felt "something like a sledgehammer" hit him in the head, he told CNN. He leaned over and saw blood everywhere.

"I wasn't aware that I was actually shot," Diggs told CNN's Brianna Keilar Wednesday. "I thought that I was just hit by a blunt object or something until I got to the hospital and saw the round in my hat."

Diggs, who serves as a Philadelphia Highway Patrol officer, suffered a graze wound to his forehead, officials said.

Despite being released from the hospital, he said he's still experiencing pain and "flashes of what happened that night."

"The fact that I could not be here to speak to you right now is something that I'm very aware of," he said. "Simply by the grace of God I was spared to, you know, continue to be on this earth."

Foster, 44, was struck in the shoulder and was also released from the hospital. He's a 17-year veteran of the Montgomery County Sheriff's Office.

Neither officer heard gunshots, Philadelphia Police Commissioner Danielle Outlaw said after the shooting. "We don't know if this was ricochet from celebratory gunfire, we don't know if this was intentional," she added. "We're just extremely grateful this wasn't worse than it was."

There have been no arrests, and no suspects are in custody. Police previously said they were following several leads and asking anyone with information to come forward.

The bullets that struck both officers were fired from the same gun and from a distance, Frank Vanore, chief inspector of the Philadelphia Police Department, said Wednesday.

"We believe based on no one hearing a gunshot and based on the way the bullet came down that they were quite a distance away and not on the footprint," Vanore said.

The shooting came nearly 12 hours after a mass shooting in Highland Park, Illinois, a suburb outside Chicago, where a 21-year-old gunman killed seven people and injured dozens more during a July Fourth parade. The shooter has been arrested and charged with seven counts of first-degree murder.

Meanwhile in Philadelphia, the police union said it would offer $20,000 for information leading to an arrest in connection with the shooting.

"We were inches away from planning a funeral for at least one brave, Philadelphia Highway Patrol officer as a bullet lodged in his cap," said John McNesby, the president of the Philadelphia Fraternal Order of Police Lodge #5, in a news release.

"There are too many guns on our streets and far too many individuals acting recklessly with these deadly weapons," McNesby added.