At least three people are dead and dozens missing after an explosion in an apartment building in southern Russia, state media reported cited by CNN.

Six people had been pulled out of the rubble as of 9:50 a.m. local time in Magnitogorsk, an industrial city in Russia’s Chelyabinsk region near the border with Kazakhstan, Russia’s Tass news agency reported, citing a statement from the Crisis Management Center of the Russian Emergencies Ministry.

Chelyabinsk Deputy Gov. Oleg Klimov said 79 people were still missing, according to Tass. A search and rescue effort is underway involving 469 emergency workers.

The local branch of Russia’s Federal Security Service said the blast was believed to have been caused by a gas explosion.

Russian President Vladimir Putin has dispatched Health Minister Veronika Skvortsova to the city, Tass reported.