Attackers fired on a bus carrying Iraqi national guard members west of Baghdad on Friday, kidnapping 15 guardsmen and leaving the bus in flames, a guard official said.
Witnesses said attackers opened fire — apparently with rocket-propelled grenades — as the guard members were heading to a local U.S. military headquarters. The attack happened near Baghdadi, about 90 miles west of the capital.
A Baghdadi guard official who identified himself only as Lt. Col. Hesham said 15 were kidnapped.
Witnesses reported unspecified casualties. Hesham said no bodies were found, but he had no other information.
Iraqi security forces — with less armor and more exposure than U.S. forces — increasingly are leading targets of Iraqi insurgents.
In other developments:
A veteran Iraqi extremist movement claimed responsibility Friday for the killing of a community leader who was working to get out the vote on behalf of the country's top Shiite cleric.
The Sunni Muslim group of Ansar al-Islam said it singled out Sheik Mahmoud Finjan for assassination as a supporter of the Grand Ayatollah Ali al-Sistani, and "as a big supporter of the elections."
A separate ambush in Iraq's north killed three officials of a party representing Iraq's Kurds — like the Shiites, working aggressively for a high turnout in a vote expected to pry a large measure of power from Iraq's long-dominant Sunni Muslim majority.
Finjan was one of many representatives of Sistani — Iraq's most influential Shiite cleric — working to get Iraq's suppressed Shiite Muslim majority to the polls in U.S.-backed Jan. 30 national elections.
Finjan was shot to death Wednesday as he headed home after evening prayers in a mosque at the town of Salman Pak southeast of Baghdad. Attackers also killed Finjan's son and four bodyguards.
The attacks were the latest blamed on Sunni extremists in what's expected to be an escalating campaign of violence aimed at intimidating would-be voters.
"We ... call upon all brother citizens not to participate in the elections because we are going to attack voting centers," Ansar al-Islam said in the statement claiming responsibility, renewing Sunni extremist demands for a vote boycott. The message was posted on a Web site used by insurgents.
Established after the Sept. 11, 2001, attacks, Ansar al-Islam is one of Iraq's older extremist groups — predating even the U.S. toppling of Saddam Hussein. The group has been linked to al Qaeda.
One of its offshoots, Ansar al-Sunnah, has emerged in recent months as the deadliest homegrown Iraqi group.
Attacks claimed by Ansar al-Sunnah include a December suicide bombing that killed 22 people, mostly Americans, at a U.S. military mess tent in the northern city of Mosul; the August executions of 12 Nepalese construction workers; and twin suicide bombings in February that killed 109 members of Iraq's assertive Kurd minority.
Many Sunni Muslim leaders say Iraq remains too violent to allow for a free election and have urged its postponement.
Anbar and Mosul's province of Ninevah are two of four provinces conceded by U.S. ground force commander Lt. Gen. Thomas Metz to be potentially too dangerous for significant voter participation.
The four, among 18 total provinces in Iraq, hold nearly a quarter of Iraq's 26 million people.