At least 20 people were killed when a gas cylinder exploded in a restaurant in central India early Saturday, while 25 people were known to have been injured, a police official said.

The explosion occurred at around 8:30 am local time (0300 GMT) at the restaurant in Jhabua district in Madhya Pradesh state as dozens of office workers and schoolchildren were having breakfast, senior district police official Seema Alava said.

“As of now, 20 people are confirmed dead. But this number could rise. Rescue efforts are on to find anyone who could be trapped inside (the debris),” Alava, additional police superintendent for Jhabua, told AFP from the site by phone.

“The restaurant was in a tightly packed locality and a lot of people were here having breakfast, that is why the casualties are so high,” she said, adding that about 25 injured people were rushed to a nearby hospital.

Alava said the intensity of the blast knocked down a neighbouring building and damaged several others. The cause of the explosion was not immediately clear.

Television footage showed scores of people and rescue workers using their bare hands to shift mangled heaps of steel and concrete of the crumbled buildings while police cordoned off the area.

Another official from the district police control room, Anurag Mishra, cited the restaurant’s proximity to a busy bus stand for the high number of casualties.

Domestic gas cylinder explosions are common in India, where safety standards are relatively poor.

And though reports of fatal accidents from cylinder blasts are frequent, mass casualties are unusual.