BAGHDAD, Iraq - Insurgents struck back with a vengeance following a post-election lull, waylaying a minibus carrying new Iraqi army recruits, firing on Iraqis heading for work at a U.S. base and gunning down an Iraqi soldier in the capital, officials said today. Two U.S. Marines were killed in action.

At least 20 people, including the Marines, died in insurgent-related incidents starting Wednesday night, according to U.S. and Iraqi reports. Insurgents had eased up on attacks following Sunday's elections, when American and Iraqi forces imposed sweeping security measures to protect the voters.

In the deadliest incident, insurgents stopped the minibus south of Kirkuk, ordered army recruits off the vehicle and gunned down 12 of them, said Maj. Gen. Anwar Mohammed Amin. The rebels allowed two of the soldiers to go free and ordered them to warn others against joining Iraq's U.S.-backed security forces, he said.

The assailants identified themselves as members of Takfir wa Hijra, an Islamic group that emerged in the 1960s in Egypt, rejecting society as corrupt and seeking to establish a utopian Islamic community.

Elsewhere, gunmen fired on a vehicle carrying Iraqi contractors today to jobs at a U.S. military base in Baqouba north of the capital, killing two people, officials said. Two civilians were killed and six injured Wednesday night when insurgents fired mortar shells at a U.S. base in Tal Afar, 30 miles west of Mosul.

A car bomb exploded at a house used by U.S. military snipers in Qaim, near the Syrian border, witnesses said. Other U.S. troops responding to the scene opened fire, hitting some civilians, the witnesses said. A U.S. military spokesman had no immediate information.

In the south, gunmen overran a police station in the city of Samawah, killing one Iraqi policeman and injuring two others Wednesday night, Japan's Kyodo news agency reported. Japanese troops are based outside Samawah.

An Iraqi soldier was killed today as assailants opened fire as he was leaving his home in Baghdad, officials said. The governor of Anbar province, a rebel stronghold west of the capital, escaped assassination today when a roadside bomb exploded near his car in Ramadi.

Gov. Qaoud al-Namrawi was not harmed, but a woman was injured when his guards opened fire.

Both Marines were killed in clashes Wednesday in Anbar province, which includes such restive cities and towns as Ramadi, Fallujah and Qaim.

The upsurge in violence occurred shortly after interim Prime Minister Ayad Allawi declared that the success of Iraq's elections had dealt a major blow to the insurgency and predicted victory over the rebels within months.