Kabul - Several blasts triggered by suicide bombers and gunfire rocked Kabul Wednesday, a day ahead of a visit by US special envoy Richard Holbrooke, causing an unknown number of casualties, police and witnesses said.

A senior police official said suicide bombers attacked the Justice Ministry, which is located in the heart of the capital near the Finance Ministry and the south gate of the Presidential Palace.

A group of four bombers equipped with machine guns stormed the ministry with one detonating himself outside the building and three others entering it, sources said.

Mahmood Jan, a ministry employee, said he saw three bodies, including a police officer's, lying on the ground and security forces had surrounded the ministry.

"The security forces came and moved us out of the building because they think two more bombers are still hiding in the building," Jan said.

In a second strike, one bomber attacked a police convoy in front of a government department that oversees the country's prisons while an accomplice entered the building, which is located in northern Kabul.

Witness Mohammad Ismail said the attacker targeted a foreign military convoy, but a police officer in the area said the convoy was passing by at the time of the blasts and there were no casualties among the foreign troops.

Tolo, a private television channel, cited security officials and witnesses in the area as saying that seven people were killed and 15 were wounded in the twin suicide bombings.

Meanwhile, police shot dead a seventh bomber who tried to enter the Education Ministry, police and witnesses said.

A Taliban spokesman, Zabiullah Mujahid, told Tolo that seven Taliban bombers had attacked government buildings in Kabul.

Kabul has witnessed several suicide attacks since the ouster of the Taliban regime in late 2001.

Suicide and roadside bombings are common tactics for Taliban militants, who have waged a bloody insurgency since their ouster against the Afghan government and the 70,000 international troops deployed in the country.

The rebel group conducted more than 120 suicide bombings in 2008. (dpa)