Moscow /St Petersburg - A car exploded near a metro station in St Petersburg on Tuesday, killing three people, including a 3- year-old child, Russian news agencies said.

The blast went off near the Udelnaya station at 8:55 am, a local Emergency Situation Ministry spokesman said.

"A preliminary investigation shows that a man, his wife and their child were killed in the blast. The car driver has got wounds and is hospitalized," news agency Interfax quoted a Russian secret services source as saying.

The source added that the explosion could have been caused by a "grenade," without giving further details.

Vladimir Markin, a spokesman for Russia's top investigative committee said a probe had been launched into the incident. (dpa)