ISLAMABAD, Feb. 21 (Xinhua) -- At least six civilians were killed and 30 others, including five policemen, were injured after three suicide bombers tried to storm a local court in Pakistan's northwest Charsadda district Tuesday morning, hospital sources said.

Mukhtar, medical superintendent of a local hospital, where all the injured people were shifted to, said that initially they received four bodies and over 30 injured at the hospital.

Mukhtar added that two of the injured people later succumbed to injuries at the hospital, bringing the death toll to six.

A member of a local bar said that the killed people also included a lawyer.

Jamaat-ul-Ahrar, a splinter group of Pakistani Taliban, in a phone call to local media claimed the attack.

Mushtaq Ghani, information minister of Khyber Pakhtunkhwa Province where Charsadda is under jurisdiction, confirmed that all three suicide bombers were killed in the attack.

He said that one of the attackers blew himself up at the main gate of the court while the two others were gunned down during exchange of fire with the police.

Ghani said that the police took quick action to counter the attack and stopped the suicide bombers from entering the premises of the court.

"Had the bombers entered the crowded court, they could have wrecked havoc by killing a large number of people," Ghani said.

Bomb disposal squad said that an estimated 9 kg of explosives were used in the attack.

Pakistani Prime Minister Nawaz Sharif condemned the attack and praised the police for successfully minimizing the casualties of the attack.