Explosion reported in southern Russia

Russian media quotes a police source as saying that a shell exploded close to the shared frontier

A shell has allegedly exploded on Russian territory, close to the border with the war-torn Donbass region of Ukraine, local media has reported.

On Saturday, Russian news agency RIA Novosti wrote that a police source in the southern Rostov region had claimed authorities were responding to the detonation in a rural community in the area. “The blast occurred at 4 am, 300 meters (984 feet) away from a house in the village of Mityakinskaya,” the official said.

The incident reportedly occurred one kilometer (0.6 miles) from the border with the Donbass, much of which is controlled by the two self-declared breakaway republics of Donetsk and Lugansk. The source said there were no casualties or damage on the ground.

In a statement issued later the same day, Russia's Investigative Committee announced that a criminal probe into the incident would be opened and that a “thorough and comprehensive investigation into the circumstances” is underway.

A second explosion has since been reported in the same region, with a law enforcement source telling RIA Novosti that a blast was heard “not far from the first one.” According to the official, the remains of a shell from a Soviet-era BM-21 Grad rocket launcher have been identified. No injuries have been reported in either case.

The Ukrainian Army and leaders from the two breakaway eastern regions have accused each other of massive shelling in violation of a signed ceasefire agreement, with a sharp spike in firefights reported over the past several hours.

READ MORE: Mobilization ordered in eastern Ukraine

Leaders in the self-proclaimed Donetsk People’s Republic (DPR) and Lugansk People’s Republic (LPR) announced that they would begin evacuating civilians to Russia on Friday in response to what they claim is an escalation in hostilities. It is unclear how many people will be relocated as part of the plans, and both regions declared that they were mobilizing their armed forces and calling up able-bodied men on Saturday for a potential conflict.