Baghdad, Iraq ? Insurgents rocketed an Iraqi military bus Friday west of the capital and 15 Iraqi soldiers were missing and feared kidnapped, as insurgent violence and intimidation escalated ahead of this month’s crucial national election.

A senior American officer acknowledged that violence and threats by insurgents might keep some people in Baghdad away from the Jan. 30 polls.

A young Iraqi street vendor stands in front of a wall covered with electoral posters featuring prominent cleric Ali al Sistani, in Baghdad. The election planned for Jan. 30 is the first democratic vote in Iraq since the country was formed in1932.

The bus was driving to a U.S. military post when it was struck by rocket-propelled grenades near Baghdadi, about 90 miles west of the capital, said an Iraqi National Guard officer who identified himself only as Lt. Col. Hesham.

He said the bus burst into flames but no bodies were found, raising fears the troops had been taken prisoner.

Elsewhere, the U.S. military announced Friday that two Marines and a 1st Infantry Division soldier were killed in separate clashes the previous day.

Iraqi police ambushed a group of gunmen in a Sunni neighborhood of Baghdad known as a stronghold of support for Saddam Hussein, killing seven, police Capt. Ahmed Ismael said. The fight occurred near the Abu Hanifa mosque, whose clerics are outspoken opponents of the election.

The bus attack was the latest in a growing number of assaults on Iraqi security forces as the country prepares for balloting.