Ten people have been found dead after an explosion and fire in a cafe in the Russian city of Orsk, emergency officials said Monday.

Authorities were trying to determine the cause of the late-night blast and fire in the city about 870 miles southeast of Moscow, Emergency Situations Ministry spokesman Viktor Beltsov said. He said all the victims were believed to have been found.

Investigators suspect it may have been an arson attack, state-run Vesti-24 television reported, citing a regional emergency official. The report said the victims, five men and five women, included the cafe's proprietor as well as employees and customers.

A spokesman for the regional branch of the emergency situations ministry, Vladislav Zubchenko, said it was unclear what sparked the fire, seemingly suggesting the blast may have been the result of the blaze and not its cause.

Without citing a specific source, Vesti-24 reported that investigators were not ruling out the possibility that the victims were killed before the fire broke out.

Zubchenko said the cafe is located at a market in Orsk, a city of about 250,000 people in the Orenburg region near the border with the ex-Soviet republic of Kazakhstan.

Firefighters extinguished the fire about 90 minutes after they were alerted of the blaze around midnight, he said.

Commercial disputes have been blamed for occasional bombings and arson attacks at offices, stores, restaurants and other establishments in Russia. Large food and goods markets are chaotic, often including a mix of ethnic groups, and sometimes the site of violence.

Russia has been plagued by terrorist attacks carried out by militants from war-scarred Chechnya and surrounding provinces in the North Caucasus in recent years, but most of the attacks have taken place in or near the North Caucasus or in Moscow.