Video: Second floor of Indonesia Stock Exchange collapses, around a dozen people injured

The second floor of the Indonesia Stock Exchange building collapsed on Monday, said an exchange employee, injuring around a dozen people who were carried on stretchers from the building.

"The second floor of the building has collapsed," said Vindy, a personal assistant to the exchange´s President Director Tito Sulistio, who was in the building at the time.

Around a dozen injured people were seen being carried from the building on stretchers, a Reuters witness said and police were cordoning off the two-tower, multi-storey building.

Investigators were sifting through the rubble  they looked for clues on what caused the incident , AFP reported on Tuesday.

Dramatic CCTV footage showed a group of about 40 visiting students on a balcony section plunge as the floor gave way with a cascade of glass, metal and other material crashing onto the ground floor where several others were walking.

National police spokesman Setyo Wasisto said the investigation team is hoping to gather crucial evidence by the end of Tuesday, though the results of the probe will not be known for several weeks.

Officials have described the collapse as an accident and not the result of an explosion -- the tower was bombed by  militants in 2000.