AR-15 rifle recovered from scene where 4 law enforcement officers killed: Police

Authorities recovered an AR-15 rifle and .40-caliber handgun from the scene where four law enforcement officers were fatally shot while attempting to serve warrants at a residence in Charlotte, North Carolina, police said.

Additional magazines and ammunition for both firearms were also recovered from the scene, where there are believed to have been more than 100 projectiles and casings, according to Charlotte-Mecklenburg Police Chief Johnny Jennings.

"I can't tell you how much I'm grateful for these officers and their heroic act," Jennings said during a press briefing on Tuesday. "To me that's truly heroic -- when you hear the gunshots and the rapid fire and they're running directly into it because they know that there are people that need help."

The law enforcement officials were shot and killed as they attempted to serve two warrants in Charlotte on Monday, city officials said. Four other officers suffered non-life-threatening injuries in the incident.

A man, later identified by authorities as Terry Clark Hughes Jr., 39, allegedly began firing at about 1:30 p.m. Monday, striking multiple officers, police said. The U.S. Marshals Fugitive Task Force had been serving active felony warrants for possession of a firearm by a felon and felony flee to elude.

The responding officers were "immediately met with gunfire," Jennings said. The shooter was firing from an upper level in the residence and had an "advantage" over them, Jennings said.

Investigators are looking into how Hughes acquired the guns and whether other shooters were involved, Jennings said Tuesday. A teenager and a woman who were in the home at the time are cooperating in the investigation, he said.

"We feel like we have everyone involved that was at the house that we need to speak with," Jennings said.

Twelve Charlotte-Mecklenburg police officers fired their service weapon during the incident and have been placed on administrative leave, per protocol, amid an investigation into the shooting, the chief said.

The four law enforcement personnel killed in the incident were identified as Deputy U.S. Marshal Thomas Weeks Jr., 48; North Carolina Department of Adult Correction veterans Sam Poloche and Alden Elliott; and CMPD officer Joshua Eyer.

"It's very tough to know that there are families that are hurting right now," Jennings said Tuesday, crying. "We'll get through it though."

The four CMPD officers who were also injured in the incident were identified Tuesday as Christopher Tolley, Michael Giglio and Jack Blowers, who were shot, and Justin Campbell, who suffered a broken foot, police said. Tolley remains hospitalized in stable condition and the others have since been released, police said.

North Carolina Gov. Roy Cooper thanked the officers who responded for their "bravery and courage."

"The investigation into this tragic, brutal, deadly attack will result in more answers that we don't know today," North Carolina Gov. Roy Cooper said at Tuesday's press briefing. "I expect it to find those answers and to help bring to justice people for these needless deaths of these brave officers."

Mayor Vi Lyles acknowledged the health care providers who "did all that was possible."

"To the four families who gave that ultimate sacrifice -- we see you," she said at Tuesday's briefing. "Today we say our prayers as we get through this difficult time."

George Dunlap, chairman of the county commissioners board, issued a statement calling the shooting a "senseless and preventable" tragedy.

The community feels "the shock and the pain" of Monday's shooting, added Dena Diorio, Mecklenburg's county manager.

"We stand ready to support our law enforcement colleagues and their families in any way we can as we all work through this heartbreaking situation," she said on social media.

Dr. Raynard Washington, the county's health director, said he was "praying and sending light & support to the families trying to make sense of this disaster" in a statement on social media.

"We should all be tired of our guns in the wrong hands problem. Here's to hope," he said.

ABC News' Julia Reinstein, Luke Barr and Jolie Lash contributed to this report.