Washington National Cathedral officials scrambled Thursday to move and reschedule some of the nation’s most high-profile Sept. 11 commemoration events after a towering crane toppled over on the historic grounds a day earlier.

The crane, with a lifting capacity of 500 tons, had been brought in to help reconstruct the more than 100-year-old iconic Episcopal structure after it was badly damaged in the Aug. 23 earthquake. But the machine toppled over just before 11 a.m. Wednesday, and officials say they still have no indication what caused it to fall.

On Thursday, two workers were hospitalizedafter another accident, but church officials said they could not elaborate on what happened.

Events at the cathedral are scheduled to begin Friday. Church officials said they quickly pivoted and started looking for other host sites. The cathedral was not damaged further by the falling crane, officials said, but events were moved because the crane had played a key role in stabilizing spires and statues atop the church that had been broken during the earthquake.

Friday’s event, a commemoration featuring military music groups and Secretary of Defense Leon Panetta, was moved to the Kennedy Center. President Obama’s planned address for Sunday was moved to the same venue, and a Saturday concert was postponed. Other Sunday events, including an interfaith prayer vigil, was moved to Washington Hebrew Congregation in Cleveland Park.

The Rev. Samuel T. Lloyd III, the church’s dean, expressed remorse for what must be one of the worst months in the cathedral’s recent history but then quickly said how thankful he was that no one was seriously injured and that events were able to be rescheduled.

“Again, some challenging times . . . following a challenging couple of weeks,” Lloyd said. “But difficult times such as this will not keep us from moving forward. It’s a hugely important time for our country.”

The crane’s operator was the only person hurt in the Wednesday accident, officials said. The operator was taken to George Washington University Hospital and treated for bruised ribs and released later the same day, said Richard Weinberg, a cathedral spokesman.

Wind gusts of 40 to 50 mph were reported in the area at the time of the accident, and the Occupational Safety and Health Administration (OSHA) is investigating.

A man reached at Crane Service of Upper Marlboro, which operates the crane, declined to comment or answer questions. The company was cited by OSHA in 2006 for not providing protective equipment to workers, and again in 2007 for failing to put up safety barricades around a crane, said Leni Fortson, a Labor Department spokeswoman.

Meredith MacKenzie, working with the church’s media team, said the cathedral served as a gathering place for mourning and reflection in the days after the terrorist attacks.

“The reason the cathedral started planning these 10th anniversary events is because they served as the spiritual home of the nation in its moment of greatest crisis,” MacKenzie said. “They feel they can once again fulfill that mission.”