The ceiling hatch of an elevator is normally locked from the outside. You may be able to pry the doors open. However, in this case, the elevator was an express

The ceiling hatch of an elevator is normally locked from the outside. You may be able to pry the doors open. However, in this case, the elevator was an express elevator and the door opened onto a cinder block wall. In the 1993 World Trade Center bombing, one group of people were trapped in an elevator, so they pried the door open, only to find drywall. They laboriously chipped a hole through the drywall with keys, reached through and felt tile. Reaching a bit more, they grabbed a paper toilet seat cover! They had made a hole into the restroom; after expanding the hole, they were able to escape. After that, the World Trade Center elevators were modified so they couldn't be opened from the inside, resulting in unnecessary deaths on 9/11.