Commissioner Richard Ross provided that update during a news conference on Friday afternoon. He said there was no indication from the suspect, 30-year-old Edward Archer of Yeadon, that he was involved in a conspiracy.
Archer allegedly told authorities he targeted an officer because police defend laws that are contrary to the Quran.
Archer had pledged his allegiance to ISIS, officials say. Ross called the shooting "an attempted assassination of a police officer."
Two law enforcement sources tell ABC News that Archer took two recent trips to the Middle East - Saudi Arabia in 2011 for Hajj and Egypt in 2012. However, he was not on a terror watch list.
Ross went on to say that Archer "stopped short of implicating anyone else in the attack," adding Archer was "very evasive."
Mayor Jim Kenney said the shooting had nothing to do with "being a Muslim or the Islamic faith."
Officials also say the gun used in the crime, a 9mm Glock 17, had been stolen from a police officer's home in 2013, but it's not clear how it ended up in Archer's hand. That officer had been disciplined, Ross said.
The shooting happened 11:40 p.m. on Thursday.
Surveillance images show a man, identified as Archer, approaching the driver's side window of Officer Jesse Hartnett's vehicle.
Images show the suspect pointing a gun at Hartnett's vehicle, while another shows what appears to be the muzzle flash as he fires.
Another image shows the gunman with his arm in the vehicle.
Ross said there was no advance warning to the officer and that the suspect "just started firing."
Police say the suspect fired a total of 13 shots, three of which hit Hartnett in the arm.
Despite being seriously wounded, Hartnett got out of his car, chased the suspect and returned fire, wounding his attacker in the buttocks, police said. Other officers chased Archer and apprehended him.
Ross called it "absolutely amazing" that Harnett survived. "It's nothing short of miraculous and we're thankful for that," he said.
"I just have to tell you, when you look at the video - we have video that captured all of this - it's one of the scariest things I've ever seen," said Ross. "This guy tried to execute the police officer. It's amazing he's alive."
The moments immediately following the shooting were also captured in a dramatic recording of police radio calls obtained by Action News overnight.
"I'm shot! I'm bleeding heavily!" Hartnett was heard saying.
Hartnett, 33, is a five-year veteran of the force. He suffered extensive injuries to his arm, but authorities say he was awake and alert prior to surgery.
The officer's father, Robert Hartnett, got to the hospital right away. After surgery, after his son woke up they were able to speak.
"I love him and very proud of him. He's an excellent person," Robert Hartnett said.
Hartnett grew up in East Lansdowne with three siblings. He went from the Coast Guard to the police academy.
"His spirits are positive," Ross said, "now that I see he's waking up. It will be a tough road. But he's a tough guy."
Archer had been arrested previously on charges that include aggravated assault and firearms violations. The FBI is assisting Philadelphia police in investigating whether he had been communicating with ISIS operatives or looking at online propaganda.
ABC News and The Associated Press contributed to this report.