At least 101 dead, 140 injured in nightclub blast, Russian authorities say

An explosion late Friday at a nightclub in central Russia killed at least 101 people and injured at least 140 others, Russian officials said.

Eighty-five of the injured were in critical condition, officials with the Russian Emergency Situations Ministry.

Explosives experts of the Federal Security Service examined the club building, the ministry said. The preliminary theory behind the blast in the city of Perm, 900 miles east of Moscow, was "unsanctioned use of pyrotechnical devices," the ministry said.

"The breach of technology while setting off a firework was the cause of the accident," said Vladimir Markin, a spokesman for the Investigative Committee of the Russian Prosecutor's Office. "It was not a terrorist act," he told Russian news agencies.