A Ukrainian citizen carrying handguns, grenades, and, presumably, mercury has exchanged fire with Russian border guards when trying to illegally cross the border, the Federal Security Service (FSB) public relations center said in a statement seen by Interfax on Monday.

"Officers of the Federal Security Service's border department in the Kursk region have detained a 31-year-old citizen of Ukraine for illegally crossing the state border into Russia," FSB said.

The man opened fire when the border guards tried to detain him and intended to escape to Ukraine.

"He sustained medium-grave injuries in the shootout," FSB said.

Two handguns, five grenades, 50 cartridges of caliber 5.45mm, and 26 ampoules presumably containing mercury were seized from the trespasser.