A charter bus full of passengers struck a bridge in Boston on Saturday night, injuring at least 32 people, authorities said.

The bus was carrying 42 people, said the Massachusetts State Police on Twitter. The passengers are high school students and their adult chaperones from the Pennsylvania area, according to the police.

Police said three people have been seriously injured.

Most of the injured suffered minor injuries, police said, and some were in the process of being released early Sunday.

Boston EMS, whose staff were also on the scene, reported that one person has life-threatening injuries. Three people had serious injuries, the emergency service tweeted, and 30 sustained minor injuries.

The bus was coming from Harvard University and heading back to Pennsylvania when it struck an overpass in the Allston neighborhood shortly before 8 p.m., according to the Boston Fire Department.

Police investigating possible charges

State Police said the Calvary Coach Bus out of Philadelphia was too high for the roadway.

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A bus bound for Pennsylvania struck a bridge in Boston, injuring at least 32 people, on Saturday, say authorities. (Twitter)

Police said they are investigating as to whether charges are warranted in the bus crash. The bus driver was not injured, according to reports from state police, and was being interviewed by the police.

"Driver believed to have missed sign prohibiting bus from that road," the police tweeted. "Did not see or heed signs warning of height limit," read another police tweet several hours later.

Ray Talmedge, owner of the Philadelphia-based Calvary Coach Bus company, said Saturday night that his driver was being interviewed by police. Talmedge, who said he didn't know anything about the road restrictions, said the driver also drives a school bus.

The students were part of a Destined for a Dream Foundation group, Talmedge said. Officials with the Bristol, Pa.-based group, a nonprofit that helps underprivileged youth, had no immediate comment on the crash.

The group's Facebook page said the trip to Harvard was to "visit the campus, sit with the office of cultural advancement, followed by a tour of the campus ... followed by Harvard Square (shopping, eating, site seeing...etc...) This should be a fun time for all!"

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A charter bus full of passengers sustained significant damage Saturday after it struck a bridge in Boston, injuring at least 32 people on board, authorities said. (Twitter)

Authorities are in the process of notifying the parents of teenagers involved in the crash, according to state police.

The bus suffered significant damage in the crash.

Photos posted on the Fire Department's website showed firefighters extracting people from the bus. Around 9 p.m. the fire department said all of the passengers had been evacuated from the bus.

The accident happened on Soldiers Field Road, a major crosstown roadway in Boston that curves along the Charles River and passes by Harvard and Boston University. It is a major roadway to the Massachusetts Turnpike.

Two heavy duty tow trucks were unable to move the vehicle over a guardrail to an adjacent road, according to the fire department. Emergency officials used fire torches to cut through the guardrail and remove it.

With files from CBC News