PHILADELPHIA (CBS) — SEPTA officials say the transit officer who was assaulted early Monday at a Market-Frankford station in Philadelphia’s Kensington neighborhood was forced to use his taser stun gun, and his alleged attacker died after being subdued. That man has not yet been identified.

Transit Police Chief Thomas Nestel says moments after peacefully escorting a man out at the Huntingdon station, as he was closing the gates for the night, that man got into an argument with another person. The officer intervened and got into a physical struggle with the first man.

Nestel describes it as an 8 minute wrestling match – while the officer called for backup on his radio – providing a narrative for his distress.

“I can only guess that our officer was struggling for what he thought was his own life,” said Nestel.

Nestel says he tells officers if they can hold on for two minutes, help will arrive, but it took backup 8 minutes, because they could not nail down his location.

“He can be anywhere between the Frankford terminal and Center City, at 2nd Street,” said Nestel.

After the man was handcuffed and while being transported to the hospital he became unresponsive, and later died.

The Philadelphia Police Homicide Unit and the District Attorney’s Office follow protocol in these matters and always investigate when a person dies in police custody. SEPTA authorities are also doing an internal investigation.

In 2015, SEPTA officers deployed tasers 55 times; and in nearly 120 other instances, they threatened to use them in difficult encounters.