A homicide car bomber hit a police checkpoint in Afghanistan's capital Friday, killing five people, including the bomber and a policeman who tried to stop him, police and witnesses said.

At least four other people were wounded in the attack in western Kabul, police chief Esmatullah Dauladzai said.

"It was a suicide attack. The attacker exploded his car when a policeman tried to stop his vehicle," Dauladzai said. There were no foreigners near the area at the time of the blast, he said.

Samiullah Ahmad Rahim, a witnesses, told The Associated Press that he heard a big explosion and saw a large fireball shortly after the blast.

The pieces of the vehicle were strewn around the road leading toward Afghanistan's parliament, and charred remains of the bomber were covered by plastic and white cloth in at least two places nearby. Windows of the nearby buildings and shops were shattered and the blast gouged a small crater on the road.

Police closed the road, and officers were collecting pieces of the vehicle and those of the bomber. Most of the shops lining both sides of the wide road were closed at the time of the blast.

No one immediately claimed responsibility, but remnants of Afghanistan's former Taliban regime have been blamed for previous such attacks.

More than 750 people have died due to insurgency related violence this year, according to an AP count based on numbers from U.S., NATO and Afghan officials.

The militants are increasingly resorting to the homicide bombings, a tactic widely used by insurgents in Iraq.

Violence in Afghanistan has soared over the last year, and officials expect spring and summer to bring more homicide and roadside attacks.

On March 28, a homicide bomber trying to blend in with street beggars in Kabul killed a top intelligence official and three other people.

That attack came a day after a homicide bomber on foot disguised in an army uniform blew himself up outside a police station in southern Helmand province, killing four police.