MOSCOW, April 4: An explosion ripped through a Moscow apartment tower on Friday, blowing out exterior walls, sparking a fire and killing at least three people, officials said.

Moscow Mayor Yuri Luzhkov said the blast was apparently caused by an accident with gas-powered welding equipment in an apartment, Russian new agencies reported.

NTV television showed footage of at least three badly damaged apartments on floors 10-12 of the 22-story building, their blacked interior walls visible because exterior panels were blown out. Smoke poured from the gaping hole torn in the side of the building, and flames leaped from at least two of the apartments.

“I was parking my car and heard an explosion, turned around and saw fragments falling and a fire,” a young man on the street said on NTV. “There was a smell of sulphur.”

Yevgeny Bobylyov, spokesman for the Moscow branch of the Emergency Situations Ministry, later said the fire was extinguished.

Luzhkov said two men and a woman were killed, but that the death toll could rise when workers remove collapsed ceiling slabs on the 10th floor, state-run RIA-Novosti reported.

Luzhkov said that renovations in an 11th-story apartment apparently led to the blast.

“We have determined the site of the explosion _ a bathroom where welding was being done at the time,” ITAR-Tass quoted him as saying. He said the explosion was “very powerful.”

Bobylyov said residents of the 20-year-old building were evacuated after the explosion.

Luzhkov said prosecutors launched a criminal investigation, suspecting that safety rules were violated, Russian news agencies reported.

The mayor said he would sign an order on Monday tightening the city's control over welding and other construction-related work in an effort to ensure it is done only by specialists with official permission.

Explosions and fires caused by accidents with gas stoves, heaters and gas canisters are common in Russia, and officials often vow stricter safety measures after deadly accidents.

A spate of apartment-building bombings in Moscow and other cities in 1999 killed hundreds of people and were blamed on militant separatists. Chechen rebels have also been blamed or claimed responsibility for several bombings in the Russian capital in the ensuing years.—AP