Operator Error Believed To Blame For Trolley Collision

Officials say a trolley collision in Boston that sent 16 people to the hospital appears to have been caused by "operator error."

Massachusetts Bay Transportation Authority Deputy General Manager Jeff Gonneville said in a statement on Saturday that the operator will remain out of service as the investigation continues.

MBTA Director of Communications Joe Pesaturo said Sunday a preliminary investigation shows the crash happened after a trolley operator did not follow the agency's safety procedures and practices.

MBTA said an inbound trolley made contact with the back of the other trolley between two stops on the Mattapan line on Friday.

Boston Emergency Medical Services said on Twitter it evaluated 17 people at the scene and transported 16 to hospitals. Authorities said none of the injuries were considered serious.

MBTA says the Mattapan Line will run with four trolleys rather than the normal set of five until it repairs the two trolleys involved in the collision.

With reporting from The Associated Press and WBUR's newscast unit