A homicide car bomber killed a policeman in an attack Tuesday on a government building in eastern Afghanistan, a day after a similar blast left four people including two NATO soldiers dead, officials said.

The car bomber tried to ram into the building in the Tani district of Khost province, but Afghan guards opened fire — causing the vehicle to explode before it entered the compound, said Khost Gov. Arsallah Jamal.

A policeman was killed and five other people, including an Afghan soldier, were wounded, said district police chief Guldat Hamim.

The attack came a day after another bomber rammed an explosives-laden car into the gates of a government building in the Yaqoubi district of Khost, causing part of the building to collapse and trapping some soldiers inside, NATO said.

Four people, including two NATO soldiers, were killed in that attack and 19 others, including 15 soldiers, were wounded, NATO's International Security Assistance Force said in a statement. NATO officials previously said only four soldiers were wounded in the explosion.

"Because of the damages, it took the recovery team an extended time to assess the number of people affected by the explosion," the ISAF statement said.

NATO did not disclose the soldiers' nationalities, but the majority of international forces in Khost are American.

Militants regularly use homicide and roadside attacks in their fight against Afghan and foreign troops in the country.

Last year was the deadliest in Afghanistan since the 2001 U.S.-led invasion. More than 6,500 people — mostly militants — were killed in insurgency-related violence, according to an Associated Press count.