Five persons were pulled out of the rubble and rescue and relief operations were underway, a district official told IANS.
The three-storey building is located in the Cantonment area. It was under dispute and Cantonment Board officials had gone to demolish it.
Local shopkeepers opposed the drive but by then one pillar of the building had been pulled down. Over a dozen persons standing inside the building were trapped under the rubble.
Cantonment Board officials and other staff members fled the scene as the building caved in.