Transit officials on Friday released the video below, which shows an outbound Green Line trolley slamming into the back of a stationary trolley at Boylston Station.
The video shows a passenger being tossed from the steps of the stationary trolley.
Boston EMS said 35 injured passengers were taken to the hospital following the collision, which happened just before noon Thursday.
Investigators have yet to determine the cause of the crash, but have ruled out mechanical or track issues, a T spokesman said.
Watch the video below: