Clean up began Thursday after a parking garage at the Broward County Courthouse collapsed.

"We were saying, this is about to go," said Frank Carreras. "Pretty mind boggling. Reminds me a bit of a war zone."

It happened at Southeast 6th Street and Andrews Avenue about 4:30 p.m. Wednesday. Cellphone video showed the garage collapse.

The security guard who was hurt was recovering Thursday as detectives tried to figure out what caused the four-story structure to collapse. A spokesperson for Broward County said another person suffered minor injuries.

The building was under demolition as part of the new courthouse construction project.

Police were reviewing surveillance video from the jail next door to get a better idea of what happened.