A mezzanine floor inside the Jakarta Stock Exchange tower collapsed on Monday, injuring nearly 80 people and forcing a chaotic evacuation.

Security camera footage circulated online showed the collapse, with a group of people plunging several meters (feet) to the ground as the structure gave way beneath them.

People fled the building through a lobby strewn with debris. Emergency personnel tended to the injured on the grass and pavement outside the tower.

National police spokesman Setyo Wasisto said most of the injured were college students from Palembang in Sumatra who were visiting the stock exchange as part of a study tour.

Wasisto ruled out terrorism as a cause of the collapse.

“There is no bomb element in the incident,” he said.

Figures released by five hospitals showed 77 people were injured.

A spokeswoman for Jakarta’s Siloam Hospital said it had received more than two dozen victims.

A college student from Palembang said she felt a tremor just before the floor collapsed.

“The structure suddenly collapsed, causing chaos,” the student, identified as Ade, told MetroTV.

She said some of her friends were hit by debris and suffered head wounds and broken bones.

The stock exchange remained open for its afternoon trading session and its general manager, Tito Sulistio, asserted no one had been killed.

“I guarantee that there were no fatalities,” he said. “I helped evacuate the victims to the park and as far as I know, the worst injuries are fractures.”

He said the exchange will pay the students’ medical costs.