Federal state and local officials sorted through debris at Boardwalk Hall on Sunday. Valarie McGonigal, the facility’s director of marketing, said the cause of the collapse – the second one at the site in three years – had not been determined.

Three stagehands sustained minor injuries when the grid came down around 12:45 p.m. Saturday at the 75-year-old landmark hall. About 30 people were working below the grid when it buckled and lurched downward before collapsing entirely.

Neither Aguilera nor Timberlake were in the building when the collapse occurred, and the Sunday concert was canceled a short time later. There was no word on whether the show would be rescheduled.

In September 2000, a similar collapse occurred during planning for the Miss America Pageant. No one was injured and the collapse did not delay the event.