Three people were killed in Bengaluru after an under-construction water tank collapsed in Amruthahalli area’s Jogappa layout on Monday morning. More than 20 people were injured, The Hindu reported.

The labourers were working on a water tank that was part of a Sewage Treatment Plant, being constructed by the Bangalore Water Supply and Sewerage Board. The workers were constructing the ceiling of the water tank when the central part of the ceiling collapsed on them. “According to initial investigation, the pillar, which was constructed to support the inside part of the tank, had developed a crack, resulting in the collapse of the centering,” a police official told The Indian Express.

More than 10 workers are reportedly still trapped and operations are under way to rescue them. The police said that the construction workers at the site were only wearing helmets and not protective suits, according to The News Minute.

Rural Development Minister Krishna Byre Gowda, Hebbal MLA Byrathi Suresh, East Zone Additional Commissioner of Police Seemanth Kumar Singh and BWSSB officials were at the spot.