A suicide attack on a district police headquarters has killed eight Afghan policemen in the country's south.

It was the second suicide bombing Tuesday of government offices in Afghanistan.

Daud Ahmadi, a spokesman in the southern Helmand province, says the policemen were killed when three suicide bombers tried to enter the police office in Musa Qala district. The police spotted the attackers, who were on foot. They killed one but the other two blew themselves up.

Ahmadi says eight policemen were killed in the blast and several others, including the district police commander, were wounded.

Earlier, a group of suicide bombers blew up their truck outside a district office in northern Herat province, killing at least 10 people.

THIS IS A BREAKING NEWS UPDATE. Check back soon for further information. AP's earlier story is below.

KABUL, Afghanistan (AP) _ A suicide blast blew up a four-wheel-drive vehicle during rush hour Tuesday outside a government office in Herat province in western Afghanistan, killing at least 10 people and wounding more than 20, authorities said.

Two men and a woman wearing a burqa were found dead inside the vehicle that exploded at the gate of a district headquarters building as people were waiting to go inside to see government officials about various business matters.

Initial reports had said only one suicide bomber was inside the vehicle and officials could not say which of the three occupants detonated the explosives.

Raouf Ahmedi, a spokesman for the police commander of the western region of Afghanistan, said police in the area had received a tip that the black four-wheel-drive vehicle was loaded with explosives.

"They were chasing the car and tried to stop it," Ahmedi said. "The vehicle then turned toward the district headquarters building and tried to pass the checkpoint, but police stopped them to be searched and asked where they were going."

Moments later the vehicle exploded, causing a loud boom that could be heard a few miles away.

"The explosion was so strong _ there are casualties among police and civilians," said Nasar Ahmad Popul, the chief of the province's Guzara district who was inside the headquarters at the time of the blast.

Ahmedi said 10 people were killed _ three policemen who were guarding the district building and seven civilians.

Twenty-seven others were wounded, including children, he said.

The Afghan Ministry of Interior said 11 people were killed and 22 were wounded. Different casualty tolls are common in the immediate aftermath of big bombings.

Barriers at the blast site were blackened and investigators examined charred remains of what was left of the vehicle. Several of the wounded were loaded into the back of police pickup trucks and taken to a hospital. Rescue workers wrapped those killed in white sheets and carried them from the site.

Herat province, as well as most of western Afghanistan, is relatively calm as insurgents have concentrated their attacks in the country's south and east. The responsibility for nearly all of the province has been transferred, or is in the process of being transferred, from NATO troops to Afghan forces.

Tuesday's attack occurred between Herat city, the provincial capital, and the main airport in the area, which is located in Guzara district.

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Associated Press Writer Deb Riechmann in Kabul contributed to this report.