A Deputy Director of the Inter-Services Intelligence agency was among the dead, media reports quoted officials as saying. Officials said five militants also died during the assault.
The Jundullah faction of the banned Tehrik-e-Taliban Pakistan claimed responsibility for the brazen attack in a statement sent to media organisations. The group's spokesman, Ahmed Marwat, said the attack was carried out to avenge the killing of commander Waliur Rehman in a US drone strike.
One attacker rammed an explosive-rigged vehicle into the high-security compound, forcing a big opening through which terrorists stormed in.
They lobbed grenades at the ISI office and engaged police and paramilitary forces in a gun battle that lasted hours.
Shehzad Abro, an official in the district police control room, told PTI that five persons died in the suicide attack and gun battle before five attackers were killed.
Reports said two terrorists blew themselves at the start of the attack while three more were killed in the gun battle.
