BOSTON (WHDH) -- Two Green Line trolleys collided just before 12 p.m. Thursday, injuring dozens.

Officials said one two-car trolley rear-ended another two-car trolley, which was unloading passengers at the Boylston MBTA Station. There was no derailment or visible damage on the trolleys.

The MBTA is calling the accident a “low-speed bump,” but the collision sent passengers flying. T officials said they ruled out problems with the signals and tracks, leading them to believe there was a problem with the trolley itself or it was human error that caused the crash.

7News has learned the driver of the second trolley which rammed into the first trolley did not have a cellphone with him, therefore texting and driving was ruled out as a possible cause of the crash.

“The other train hit us from behind. It felt like getting rear ended in a car, only on a larger scale,” said Corinne Conley, an Emerson College student. “Luckily I was holding on, but everyone around me went flying forward.”

Conley said her train was pretty full as people were still getting on, she said people were crying and some were bleeding when the two trains hit, though the injuries were minor.

“One of my friends was getting on the train, on the stairs, when it hit and she fell down the stairs into other people. She hurt her knee and her arm and her head,” said Conley.

Some passengers complained of back and neck pain, but no life-threatening injuries were reported. EMTs set up a triage area outside the station, some people were on backboards with neck braces. Boston EMS said at least 35 people needed to be treated; at least nine of those passengers were taken away on stretchers.

Several passengers were checked out inside an MBTA bus, which was brought in to provide warmth. Some of those people also ended up in ambulances.

“Another 26 we evaluated for minor injuries -- bumps, contusions, they’re all adults -- 35 total were evaluated,” said Chief Jim Hooley, of Boston EMS.

Three MBTA employees, including both operators, were among those transported to the hospital with minor injuries.

The accident will be investigated by the Transit Police. It is too early to tell the cause, but the State’s Secretary of Transportation promises a thorough investigation.

“We will look at the mechanical issues, if there were any on the train. We’ll look at potential signal or track issues as we always do and we will look at operator error,” said Richard Davey, the Secretary of Transportation.