Iraqi medics treat a wounded man at a hospital in Kirkuk, 04 Apr 2007

Iraqi police say gunmen have ambushed a bus carrying workers of a power plant in northern Iraq, killing at least five people.

Police say the attack took place Wednesday near the town of Hawija, about 70 kilometers southwest of the oil city of Kirkuk.

Separately, the U.S. military says coalition forces captured nine suspected terrorists during raids across Iraq, near the northern city of Mosul, near Karmah and in the town of Habbaniyah, west of Baghdad Wednesday.

Meanwhile, Iraqi authorities announced the shortening of the nightly curfew in Baghdad - in a sign the government believes a U.S.-Iraqi security crackdown is having a positive impact in the capital.

Officials say starting Wednesday the curfew will begin at 10 p.m. (local time) and last for seven hours.

Since the start of the security crackdown in mid-February, the military had enforced a 10-hour curfew beginning at 8 p.m. (local time).

The joint U.S. and Iraqi military crackdown has reduced sectarian violence in Baghdad.

However, car bomb attacks in the capital are continuing. And, insurgent groups also have been carrying out attacks in other towns and cities.

Iraqi officials said about 20 people were killed or found dead across the country Tuesday.

Some information for this report was provided by AFP and Reuters.