PHILADELPHIA -- Police in Philadelphia are investigating a tip that a man charged in the ambush shooting of a patrolman is connected to a larger, radical group that may continue to pose a threat to officers.
The police department said Sunday evening that someone approached an officer on the street over the weekend and alleged that the man who attacked Officer Jesse Hartnett -- allegedly 30-year-old Edward Archer -- "had an affiliation to a group with radical beliefs."
According to CBS Philly, the person said Archer is "part of a group that consists of three others." She added that the suspect "is not the most radical of the four" and that "the threat to police is not over."
Police and the FBI are trying to determine whether or not the information is credible. For now, the department says all officers must work with a partner.
Police say they are working with the FBI to investigate the credibility of the information. They have alerted all department employees about the tip and will continue to require officers to work with a partner until further notice.
Harnett was last reported in stable condition at the hospital after a man charged his car as he patrolled his usual west Philadelphia beat shortly before midnight Thursday, firing at least 13 shots, hitting the officer three times. Hartnett got out of his car, chased the man and returned fire, wounding him in the buttocks before he was captured by other officers about a block away.
Edward Archer, 30, of Yeadon, was charged Saturday with attempted murder, aggravated assault, assault of a law enforcement officer and several firearms crimes. He is being held without bail pending a Jan. 25 preliminary hearing. The Defender Association of Philadelphia, listed in court documents as representing him, couldn't be reached over the weekend to offer comment on the charges.
At a news conference, Philadelphia Police Commissioner Richard Ross, who just took office Tuesday, didn't label the shooting a terrorist attack, though he said Archer "clearly gave us a motive."
"It wasn't like laying it out completely, chapter and verse for us," Ross told reporters at the department's headquarters as Archer was being questioned upstairs. "We're left to say, 'OK, he's leaving a trail for us. Where's it going to lead us, if anywhere?'"
Ross told CBS News correspondent Jericka Duncan his biggest regret was that the firearm used was stolen from a fellow police officer's home in 2013.
"It cuts deep," Ross said. "I mean, things happen, but it cuts deep and deeper."
Surveillance footage of the attack showed Archer dressed in a white, long-sleeved tunic. When asked if the robe was considered Muslim garb, Ross said he didn't know and didn't think it mattered.
"We've already established why he believes he did it, and that's probably enough," Ross said.
Jim Kenney, in his first week as mayor of the nation's fifth-largest city, called Archer's actions "abhorrent" and "terrible" and said they have nothing to do with the teachings of Islam.
"This is a criminal with a stolen gun who tried to kill one of our officers," he said. "It has nothing to do with being a Muslim or following the Islamic faith."
Investigators said Archer told them he was "following Allah" and pledged allegiance to the Islamic State of Iraq and Syria (ISIS), and he believed the police department defends laws that are contrary to Islam.
Authorities believe Archer traveled to Saudi Arabia in 2011 and to Egypt in 2012 and are investigating the purpose of those trips. FBI special agent Eric Ruona said Sunday that as U.S. authorities work with partners overseas, it would take time to find any potential terror connections, and it was too early for any meaningful comment on the subject.
Archer's mother, Valerie Holliday, described her son as devout Muslim. Jacob Bender, the executive director of the Philadelphia chapter of the Council on American-Islamic Relations, an advocacy group, said he contacted about five inner-city mosques and found no one who knew of Archer.
Earlier, police said a man tried to grab the gun of a Philadelphia officer working a detail at the hospital where Hartnett is recovering, but they believe the incident is unrelated to the ambush shooting.
Police said the man approached the officer outside Penn Presbyterian Medical Center shortly after 10:30 p.m. Saturday and asked for money, saying he hadn't eaten in five days.
The officer handed the man a $5 bill and entered the medical center, but later, when he was standing near the emergency room exit doors, the man tried to grab the officer's handgun from the holster. The officer, with the aid of hospital security and other officers, subdued the 40-year-old suspect, who said he wanted the gun to rob a store, police said.
Police said the incident appeared unrelated to Hartnett's shooting but was "an example of the type of individuals that our officers face daily when performing their duties as Philadelphia police officers."
Meanwhile, a fundraising page has been set up to raise money to help pay the expenses of the wounded officer, who was shot three times in the arm and will require multiple surgeries. The GoFundMe page had recorded $17,530 on Sunday afternoon.