One official said the blast went off in an elevator as the commander of the intelligence service, Gen. Tareq Abu Ghajab, was in the area. It was not immediately clear if the general was among those hurt.

The wounded were driven to a nearby hospital in cars of the intelligence service. Fellow agents fired in the air from the windows of the vehicles to clear the way.

The blast came at a time of growing tension between the Hamas government and the Palestinian security forces loyal to moderate President Mahmoud Abbas.