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ROSTOV-ON-DON, Russia (AP) _ A bus passenger set off a grenade during a brawl Thursday, killing four people and wounding six, a spokesman for the Emergency Situations Ministry said.

The explosion was not believed to have been a terrorist act, said Yuri Kolodkin, of the ministry's southern Russia district.

He said the dead included the man who set off the grenade.

The blast took place in Malgabek, a town in the republic of Ingushetia.