At least seven people, including two children, were killed in Russia on Tuesday when a gas explosion caused part of a block of flats to collapse.

At least seven people, including two children, were killed in Russia on Tuesday when a gas explosion caused part of a block of flats to collapse, officials said.

"Due to the explosion, one section of a five-storey residential building collapsed" in the city of Yaroslavl north of Moscow, the regional emergencies ministry said in a statement.

"Five flats have been completely destroyed. Seven people died, including a teenager and a five-year-old child," it said. The incident happened around 4:20 am (0120 GMT).

Three injured people rushed to hospital while authorities evacuated 131 residents and put them in temporary housing.

A spokeswoman for the emergencies ministry told AFP the reason for the blast was not yet clear but Russia's Investigative Committee said it had launched a probe into possible safety violations.

The governor of the Yaroslavl region, Sergei Yastrebov, said work was ongoing to check whether it was safe for other residents to pick up their belongings from the part of the building still standing.

Explosions caused by natural gas leaks are frequent in Russia, especially in older Soviet-era buildings.

The last serious gas explosion in February 2012 killed 10 people in the southern city of Astrakhan and destroyed the entire side of a nine-storey building.