The crowded second floor of a Tallahassee, Florida, apartment building collapsed early Sunday - sending scores of people plummeting and, ultimately, 55 to area hospitals - city authorities said.

None of the injuries suffered in the collapse at the Seminole Grand Apartments are considered life-threatening, according to a release on the Tallahassee city government's website.

Witnesses reported an "unusually large crowd" in the two-story, wood frame building before the city fire department got a call at 1:27 a.m. about the collapse.

Using a ladder truck, firefighters rescued seven people after they became stuck in a second-story bedroom and could not access the stairwell, the city said. No one was trapped under the collapsed floor, and the first floor did not contain any apartments.

The building opened for occupancy in December 1995, according to the city. The cause of the collapse - which early estimates suggest caused $250,000 in damage - is under investigation.