One man was injured in a household gas explosion...

A law enforcement spokesman said the explosion occurred in an apartment on the fourth floor of a 14-story building on Artekovskaya Street, adding that some walls in the apartment and stairwell windows were smashed by the shock wave.

"The man — the owner of the blast-affected apartment — was injured. He was hospitalized to the 36th city hospital," the spokesman said.

Immediately after the blast, the man, shocked, left the building, and was discovered some time later.

It was not immediately clear what caused the blast. An investigation is underway.

MOSCOW, January 21 (RIA Novosti)