One other policeman was hospitalized in critical condition following the attack in Chegem, a small town in the Caucasus province of Kabardino-Balkaria, Alexei Kolupayev, a police spokesman for the North Caucasus Federal District, told The Associated Press.
The suspects escaped with their Kalashnikov rifles in a commandeered taxi, Kolupayev said.
Law enforcement officials come under regular attack in southern Russia from Islamist rebels seeking an independent Caucasus emirate. Human rights activists say the violence is provoked by the mistreatment of peaceful locals by authorities under the pretext of fighting extremism.
The region is a breeding ground for terrorism, with Caucasus rebels claiming a number of deadly attacks across Russia in recent years. Last week's suicide bomb attack at Moscow's busiest airport, which killed 36 people and wounded scores more, had the hallmarks of a Caucasus insurgency operation. No one has yet claimed responsibility, though investigators say the bomber was from the region.
In Dagestan, another Caucasus province, two suspected insurgents were killed in an overnight gunbattle with police.
Police said the two men were killed after blockading themselves in a house in the village of Shamkhal. A gun stash was discovered when the house was raided, police said, adding one of the men was an escaped convict.
And in the nearby town of Kizlyar, three people were wounded in a bomb blast at a food store late Tuesday, police said.