MOSCOW (AP) — A gas explosion in an apartment building outside Moscow on Wednesday killed two people and injured five others, law enforcement officials said.

The blast occurred in a nine-story building in Noginsk, a town 50 kilometers (about 30 miles) east of Moscow. The blast affected the lower part of the building, with three stories appearing to have sustained the most damage. About 30 apartments were damaged. Local authorities evacuated 170 people from the building.

A man and a woman were killed, and five other people sustained injuries, according to the Moscow region’s branch of Russia’s Investigative Committee. The state Tass news agency said that a total of 51 people have been rescued and evacuated from the damaged part of the building.

The agency cited local emergency officials as saying that 13 people have sustained injuries, and six of them have been hospitalized. The varying numbers of those wounded could not be immediately reconciled.

The authorities launched a criminal probe into the explosion as is common in such cases. The governor of the Moscow region, Andrei Vorobyov, headed to the site of the blast.