MOSCOW  Heavily armed gunmen burst into the Parliament building of Chechnya, in southern Russia, on Tuesday morning, killing at least three people and wounding more than a dozen before the assailants were killed by police officers or by their own explosives, officials said.

The assailants, including one suicide bomber, sprayed automatic rifle fire and set off at least one explosion in one of the most brazen assaults to occur for some time in Chechnya, a region in the volatile North Caucasus where violence linked to a simmering Islamist insurgency is common.

The police were able to prevent the militants from reaching Parliament members’ chambers, investigators said, though the men were able to barricade themselves on the first floor and open fire.

Investigators said that three gunmen drove through the front gates of the Parliament complex, in a busy section of downtown Grozny, Chechnya’s capital. Without uttering a word they killed two police officers standing guard at the entrance, said Alvi A. Karimov, the press secretary for Ramzan A. Kadyrov, Chechnya’s leader. One militant then blew himself up, killing a staff member, Mr. Karimov said. The force of the blast blew out windows and wounded several others.