The pipeline exploded shortly after Victory Day celebrations, sending flames 100-300 meters into the air. Five people were treated for burns and some 30 cars were damaged by the blaze, the ministry said.
A police source earlier told RIA Novosti that the pipeline could have been damaged intentionally. He added that bomb experts of the Russian Interior Ministry and Federal Security Service would start investigating causes of the explosion as soon as the fire is extinguished completely.
Meanwhile, Moscow Mayor Yury Luzhkov who arrived at the site of the explosion said the incident was of technogenic nature. It was acknowledged Moscow's largest fire since World War II.
Some 100,000 telephone users were left without telephone and Internet communication, after the fire destroyed or damaged telephone cables, the Russian Emergencies Ministry said.