In one instance, SEPTA police say they'd been on the lookout for Ernest Hayes wanted for running a fare scam.
Officer Samuel Washington spotted him along the Broad Street Line at the Cecil B. Moore stop.
When Washington tried to apprehend him, surveillance video shows that Hayes slammed the officer into a bench and pinned him.
"Actually trapped him underneath a bench on the platform and had Officer Washington on his back holding onto the suspect for dear life," SEPTA Police Chief Tom Nestel said.
Officer Washington injured his back and remains off the job.
Just as troubling for police is the alleged attack lasted several minutes and police say none of the passengers called for help.
At least one person recorded the officer under assault on a cellphone.
"It's frustrating. It's discouraging to see that people will let a police officer get assaulted like that and not call 911," Nestel said.
Passengers Action News interviewed say they'd like to help, but many conceded there can be a tendency to just watch.
Last Thursday, a day after Officer Washington was allegedly attacked, two plain clothed officers tried to apprehend a juvenile jumping onto the tracks.
Again, officers found themselves in a struggle.
Passengers just stood and watched and no one summoned help.
Nestel says police don't want bystanders to intervene, but they can provide assistance.
"The message is call 911 and say that an officer needs help," Nestel said.