ROSTOV-ON-DON, September 11 (RIA Novosti) - A suspected suicide bomber died and five people were injured during an attack on a police checkpoint in Russia's North Caucasus republic of Ingushetia on Friday, a police source told RIA Novosti.

The source said that the driver of the Lada vehicle died when his car blew up near the checkpoint, not far from the republic's largest city of Nazran.

"At the same time, heavy shooting came from a nearby graveyard," the source said.

"It's not a fact that he was a suicide bomber," the source said. "The explosives could have been put in his car and detonated from a distance," he went on, adding that investigators were looking into the incident.

Five other people, two police officers and three civilians were injured. One of the civilians is in a serious condition.

Initial reports said the Lada driver was the only casualty.

Russia's North Caucasus has been plagued by frequent militant attacks recently. In August, over 20 police officers were killed when a suicide bomber attacked a police station in Nazran.