Visitors on the observation deck of the world’s tallest tower in Dubai heard what sounded like a small explosion, then saw dust that looked like smoke seeping through a crack in an elevator door 124 floors above the ground. The 15 people inside were trapped for 45 frightening minutes until rescuers managed to pry open the doors.

Because the elevator was apparently stuck between floors, rescuers had to drop a ladder into the shaft so those inside could crawl out. On the observation deck, about 60 more people were stranded and some began to panic.

Shortly after the drama unfolded on Saturday evening, the half-mile-high tower that was supposed to be one of Dubai’s proudest achievements shut down to the public one month after its grandiose opening. It was the latest embarrassment for the once-booming Gulf city-state that is now mired in a deep financial crisis.

Witnesses who were on the 124th floor observation deck at the time and a Dubai rescue official recounted on Tuesday the chain of events that led up to the shutdown in interviews with The Associated Press.

Emaar Properties, the state-linked company that owns Burj Khalifa, has said little about the incident and nothing at all about an elevator malfunction. It had no comment on Tuesday. It remains unclear what caused the elevator to the observation deck — the only part of the building that was open — to fail.