Police are searching for two men believed to be involved in the explosion that ripped through a Russian apartment block today, killing at least 21 people and trapping dozens in the rubble.
Police in the northern city of Arkhangelsk said that residents of the neighbourhood where the blast occurred had seen two men carrying metal pipes and instruments.
Police believed the men could have opened pipes carrying natural gas to the building, ITAR-Tass news agency reported.
Authorities refused to rule out terrorism amid heightened tension in Russia after a series of attacks blamed on Chechen rebels.
Firefighters reported a strong smell of gas, and gas employees said leaks had been reported in other Arkhangelsk buildings overnight.
A spokesman for the regional Federal Security Service agency said that no explosive devices were found.
The blast hit when most of the 80 residents registered in the building in Arkhangelsk, about 600 miles north of Moscow, were sleeping, said an Emergency Situations Ministry spokeswoman.
AP