MOSCOW - At least two people died and five others trapped when a gas blast hit a residential building in Moscow region Monday, authorities said.

The explosion occurred at around 9:30 am Moscow time (0530 GMT) at a nine-story building in Sergiyevo Posad district of Moscow region, causing partial collapse of four flats between the eighth and ninth floors.

"The rescuers have found two people dead under the debris, including a woman and a child," Itar-Tass news agency quoted an unnamed source in the emergency center as saying.

It said earlier one man died immediately at the scene.

Two people have been hospitalized and five more may remain under the debris, the Emergency Situations Ministry's central regional center told reporters.

The cause of the blast is yet to be determined. Rescue teams are working at the scene.