The MBTA has released surveillance video of Thursday's trolley collision at Boylston station.
Dozens of riders were injured when two Green Line trolleys bumped inside the station. The video clearly shows one trolley stopped with passengers boarded when it's suddenly bumped from behind.
The first trolley lurched forward and passengers were knocked off their feet. One man fell backwards out of the trolley, stood up, then doubled over and laid down before crawling back into the car to pick up personal items.
The MBTA has ruled out mechanical errors and is now focusing on whether driver error was the cause of the crash, according to Boston.com.