VOLGOGRAD, December 30 (RIA Novosti) – An explosion went off on a trolleybus in Russia’s southern city of Volgograd on Monday morning, killing at least 10 people in the second fatal blast in the city over the past day.

Russia’s Investigative Committee Spokesman Vladimir Markin said the trolleybus explosion was a terrorist attack, making it the second such incident in Volgograd in less than 24 hours.

A bomb explosion at a railway station in Volgograd on Sunday afternoon killed 17 people, in what authorities said was an attack by a suicide bomber. Investigators have arrived at the location of the trolleybus explosion.

The blast was most likely caused by an explosive device left in the vehicle’s passenger cabin, Russia’s National Anti-Terrorism Committee said.

In another attack in Volgograd in late October, six people were killed and 37 injured when a bomb carried by a young woman from the southern republic of Dagestan detonated while she was travelling on a crowded commuter bus.

The cities blighted by those attacks are located close to the North Caucasus, a multiethnic and volatile region that suffers near-daily attacks on officials, police and civilians by local militant groups.