One side of the curved staircase at the historic Union League building was damaged overnight by a thief who made off with its brass railing, a spokesperson for the club said.

A male suspect was caught on security footage ripping an approximately 6-foot portion of the railing from the building's stone steps just after 3 a.m. Monday.

"He is seen on tape walking down Broad Street to Moravian, and he hid it behind some dumpsters for a minute," a spokesperson said, explaining the move was likely to divert attention. "Later, he is seen on camera coming back for it and leaving with it … he seemed to struggle [holding the railing]."

The suspect's face cannot be seen in the surveillance video, though it appears to be a man wearing heavy clothing.

The damage runs halfway up the right-side staircase leading up to the club's front door. Portions of the stone railing fell onto the sidewalk below. The Philadelphia Inquirer first reported the damage on Monday. 

Anthony Collins, a security guard at the building, said that officials were reviewing security footage. 

Collins said when he arrived to work at 6 a.m., the area had already been taped off. There's a security guard at the Union League building at all times, he added.

The Union League's spokesperson said the overnight security guard didn't hear the incident, but discovered the damage shortly thereafter. 

"it is a very sad day for sure," the spokesperson said.

The railing was redone recently, but made in the building's original 19th-century design, the Union League said. Experts will assess the damage and make a determination on repairs later.

Built in 1865, the Beaux Arts-style building at 140 S. Broad St. is open to members only, and was added to the National Register of Historic Places in 1979. It recently completed $12 million in renovations.