Security officials examine the blast site in northwest Pakistan's Mardan, Sept. 2, 2016. (Xinhua Photo)

ISLAMABAD, Sept. 2 (Xinhua) -- At least four people were killed and 24 others injured in a suicide blast on Friday in Pakistan's northwestern district of Mardan, officials said.

Rescue officer Haris Habib said they have shifted four bodies and 24 injured to hospital from the site so far, adding that six of the injured are in critical condition.

According to media reports, the incident took place when a suicide bomber tried to enter the district courts in Mardan, but he blew himself up at the entrance gate when police guards asked him for body search.

The bomber also hurled a hand grenade to people inside the court area.
No group has claimed responsibility for the attack yet.

Photo taken on Sept. 2, 2016 shows the roof of the blast site in northwest Pakistan's Mardan. (Xinhua Photo)