PHILADELPHIA (CBS/AP) —Federal investigators will send a team to Philadelphia after nearly 50 people suffered various minor injuries when two Southeastern Pennsylvania Transportation Authority trolleys collided in west Philadelphia on Thursday.

The NTSB says the team will look at collision avoidance and federal oversight issues, which are on their “most wanted list”.

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The Route 10 trolleys were headed west in the Powelton Village section of the city when one of the trains rear-ended the other near 38th Street at about 1 p.m. Wednesday.

SEPTA officials say none of the injuries were considered life-threatening. A total of 44 passengers were hurt along with the two trolley operators.

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One passenger described the impact as like if a bomb had been set off. The circumstances of the accident remain under investigation.

SEPTA officials say they aren’t sure why the trolleys were running so close to each other. Trains typically run on a schedule about 10 minutes apart.

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