At least 82 people have been killed in a powerful explosion that tore through a restaurant in Petlawad in the Indian state of Madhya Pradesh, officials say.

It was packed with workers and schoolchildren eating breakfast.

The exact cause of the blast is unclear. Police first said a cooking gas cylinder exploded, and later added that explosives being stored nearby may also have caught fire.

Rescue efforts are continuing and nearby buildings have been evacuated.

At least 35 people are in hospital with injuries, officials say.

Police have struggled to keep hundreds of onlookers and people looking for their relatives away from the site, officers told the Associated Press news agency.

The restaurant was close to a busy bus stop. The blast knocked down a neighbouring building and damaged several others.

“It looks like someone had stored those explosives, the ones used in mining, in one of the buildings. But only further investigation will reveal the exact details,” the AFP news agency quotes senior district police official Seema Alava as saying.

Petlawad is in Jhabua district where there are several manganese and bauxite mines and, according to AP, many mine workers are hired on contract from the town, which is about 850km (530 mile) south of the capital, New Delhi.