MILLVILLE, N.J. (CBS) – A century-old theatre undergoing renovation in Cumberland County, New Jersey collapsed Monday afternoon.

Authorities say the exterior walls of the Levoy Theatre in Millville gave way at about 4 p.m.

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Minutes before the first wall came crashing down, workers inside the theatre noticed part of the building shift. Fortunately all of the workers made it out with no injuries.

Millville firefighters called to the historic theatre after the first wall came crashing down were inside a neighboring building when the theatre suddenly collapsed.

A 25-year veteran of the Millville Fire Department broke his leg after being struck by falling debris. He was treated and released by Monday evening.

The theatre, located on N. High Street, was in the midst of an $8.5 million restoration project.

Parts of the theatre were recently demolished, and reconstruction was set to begin soon.

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Emergency crews are worried about the structural integrity of the two buildings next to the collapsed theatre. There is concern the other buildings could also come down.

Approximately 20 people who live near the collapsed structure have been temporarily evacuated as a precaution.

The Red Cross is helping find temporary shelter for the estimated 20 people who were displaced.

“It’s devastating, no question about it,” Millville Mayor Tim Shannon said.

The original Levoy Theatre, according to its web site, was built in 1908 by William “Pop” Somers of Somers Point fame and it hosted silent films and vaudeville acts.

The cause of the collapse remains under investigation.

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Reported By: Todd Quinones, CBS 3