An explosion on a bus carrying air force personnel killed 13 people Thursday in southern Russia near Chechnya, the ITAR-Tass news agency reported.
The bus was traveling from the city of Mozdok in the North Ossetia region to a military airbase neaby, ITAR-Tass reported, citing unnamed officials at Russia's main military base in Chechnya.
The cause of the explosion was not immediately known.
Mozdok is the headquarters for Russian forces fighting rebels in Chechnya.
Russian forces left Chechnya in 1996 after 20 months of fighting separatist rebels bogged down into a violent stalemate. They returned in 1999 after Chechnya-based insurgents made raids into neighboring Dagestan and after some 300 people died in apartment bombings that Russian officials blamed on the rebels.