Hundreds of Taliban fighters attacked a western Afghan government building with rocket-propelled grenades and machine guns Monday, killing three police officers and wounding seven in one of the militia's boldest strikes in the long-quiet region.

The attack in Farah province could reflect a drive by militants to expand their fight against Afghan and U.S.-led coalition forces beyond insurgency-wracked southern and eastern provinces.

The battle came amid a flurry of suicide attacks, roadside bombings and shootings across the country.

Four suspected suicide attackers riding on two explosives-laden motorbikes in Farah province were killed after they were challenged by police while driving through the provincial capital late Sunday, said Gen. Sayed Aga Saqib, the provincial police chief.

Two of the suspected attackers were fatally shot. The other two were killed when police shot at their bike and detonated their explosives.

A boy walking nearby was killed in the explosion, while the child's father was wounded, Saqib said.

CountryWatch: Afghanistan

Near Kandahar, a suicide car bomber seriously wounded two U.S.-led coalition soldiers. Also, gunmen killed two Afghans delivering medicine for international aid agency World Vision.

The heaviest fighting was in the town of Bakwa in Farah province, which had been spared the worst of the violence between resurgent Taliban-led rebels and Afghan and foreign troops that has killed more than 800 people, mostly militants, since mid-May.

About 400 Taliban fighters in about 35 pickup trucks arrived in the town late Sunday and launched a heavy assault on a district police and administration headquarters using dozens of machine guns and rocket-propelled grenade launchers, Saqib said.

The militants fled back toward neighboring Helmand province after a five-hour battle, carrying an unknown number of militant casualties.

A suicide car bomber seriously wounded two U.S.-led coalition soldiers when he rammed their convoy as they patrolled with Afghan army soldiers in southern Kandahar province, on the main highway toward the capital, Kabul, coalition spokesman Col. Tom Collins said.

The coalition declined to identify the wounded soldiers. Maj. Scott Lundy, another coalition spokesman, said their injuries were "serious but not life-threatening."

In western Ghor province, gunmen killed a doctor and a driver for the aid agency World Vision, said Karimuddin Razazada, deputy governor of Ghor province.

In eastern Afghanistan, an attacker traveling in a taxi from neighboring Pakistan exploded two grenades at a border police checkpoint in Khost province late Sunday, killing a civilian and wounding three others, police said.

Afghanistan is experiencing its worst violence since late 2001, when the Taliban regime was overthrown in a U.S.-led invasion.

The most intense fighting has been in the south, where NATO is bolstering its presence as it prepares to take over security duties in the region from the U.S.-led coalition by the end of the month, increasing troop numbers increased from 9,700 to 16,000.

It is one of the biggest and most dangerous missions in NATO's history and has been met with stiff resistance from Taliban-led fighters, who appear to be increasingly adopting methods used by militants in Iraq.