Originally Published: 18 OCT 21 12:42 ET

Updated: 18 OCT 21 13:48 ET

By Eric Levenson, CNN

(CNN) -- A man was arrested for allegedly sexually assaulting a woman on a SEPTA train in Philadelphia last week, even as a number of witnesses failed to stop the incident or call police, authorities said.

The alleged rape occurred on SEPTA's Market-Frankford Line last Wednesday night and was a "horrendous criminal act," SEPTA said in a statement. The public transit authority said other people on the train saw the incident and did not alert authorities.

"There were other people on the train who witnessed this horrific act, and it may have been stopped sooner if a rider called 911," SEPTA said. "SEPTA urges anyone who observes a crime being committed or any dangerous situation occurring to report it. Anyone witnessing an emergency should immediately call 911."

SEPTA spokesperson Andrew Busch said an employee in the vicinity of the incident as the train went past called police to report that "something wasn't right."

"The SEPTA employee boarded the train and saw the assault in progress and immediately called 911. That prompted an immediate response by SEPTA Transit Police, and an officer boarded the train when it arrived at the 69th Street Transportation Center," Busch said in a statement. "The officer located the suspect and the victim, and took the suspect into custody."

The Upper Darby Township Police took the lead on the case because they have a Special Victims Unit, he said.

The suspect was identified as Fiston M. Ngoy, 35, who had preliminary arraignment last Thursday on charges of rape, sexual assault, aggravated indecent assault and more, according to court documents.

He is being held at Delaware County Prison on 10% of $180,000 bail and has a preliminary hearing scheduled for next Monday, the documents state. CNN has not been able to reach Ngoy for comment.

Upper Darby Police superintendent Tim Bernhardt said the suspect did not know the victim, whom he praised for coming forward, according to CNN affiliate WPVI.

"Unbelievably strong woman. She really is. She came forward, she provided a lot of information. She's on the mend, and hopefully she will get through this," he told WPVI.

The entire incident was captured on video surveillance, and Bernhardt said investigators plan to go through the video to understand the incident, as well as what other SEPTA riders were doing.

"There were a lot of people, in my opinion, that should have intervened. Somebody should have done something," Bernhardt said.