A member of St Petersburg's elite anti-organized crime task force died after being riddled with bullets in a fierce city-center gun battle with gangsters.
Lieutenant Vladimir Trotsenko, 28, who was shot eight times, died in the Kirov Military Hospital an hour later despite frantic efforts to save his life.
More than 500 members the notorious Kazanskaya crime gang have been rounded up in the hunt for his murderers.
Lt Trotsenko, a married man with a four-year-old daughter, came under fire as he and two fellow RUOP officers mounted an undercover operation on Suvorovsky Prospect, next to Smolny Cathedral.
The plain-clothed policemen were waiting in their unmarked Audi for the arrival of a gang suspected of a series of kidnaps.
Witnesses said two jeeps suddenly arrived and surrounded the officers' vehicle before four well-dressed men got out and took aim.
Lt Trotsenko cried out, "Freeze, it's the police," before he was wounded in a hail of bullets.
He managed to turn his gun on his attackers and fire three shots before he lost consciousness. None of the gang were seriously injured.
A 23-year-old passer-by was also caught up in the exchange of fire and suffered a bullet wound to the stomach. A second officer was knocked unconscious when one of the thugs punched him in the face before the jeeps sped away from the scene of the tragedy.
Taxi driver Vladislav who witnessed the shooting said the policemen were attempting to film the gangsters at the time.
"They probably didn't even realize they were policemen," he said. "They just thought they were members of a rival gang."
Police said three suspects were rounded up within an hour of the killing. A bullet-ridden jeep was confiscated.
That night RUOP officers targeted nightspots in their hunt for the rest of the gang. They detained 555 men and seized 25 firearms including a Chechen-made Borz automatic.
"In the wake of the massive operation sparked off by Lt Trotsenko's murder, the number of crimes registered daily in St Petersburg has dropped by about 20% since most criminals have decided to keep their heads down until the heat is off," said police spokesman Major Igor Komissarov.
Lt Trotsenko was buried with full honors at a ceremony in the Bolshe-okhtinskoye Cemetery attended by the city's top police officers.
Maj Komissarov said, "The bandits would have shot down all three men in the police car if Vladimir had not opened fire."