Police and other law enforcement agencies responded to a report of an “active shooting” in the North Philadelphia neighborhood of Nicetown-Tiago, Sgt. Eric Gripp, the police spokesman, said on Twitter.
Authorities have repeatedly urged residents to stay away from the area because shots were still being fired.
“Suspect is still firing. STAY OUT OF THE AREA,” Gripp said.
Video from a news helicopter showed more than 50 police vehicles at the scene. It also showed police officers kneeling and crouching behind various cars with guns drawn.
Temple University put its Health Sciences Center, about 2 miles from the standoff, on lockdown, school spokesman Ray Betzner said.
“Seek shelter. Secure doors. Be silent. Be still. Police are responding,” the university said on Twitter. More than an hour later, the university continued to advise students to “stay indoors away form windows.”
Six police officers have been shot, Gripp said.
The officers, who were not immediately identified, were taken to area hospitals with non-life threatening injuries, he said.
CNNs Laura Ly, Steve Almasy, Dave Alsup, Mark Moraels and Chris Boyette contributed to this report.