At least six paramilitary troops and six suspected militants were killed in northwestern Pakistan Tuesday after militants attacked a security forces compound, sparking an hourslong operation, police and rescue officials reported.

Another 20 people, including security personnel, were injured, said local rescue department officials.

Suspected suicide bombers rammed an explosive-laden vehicle into the main gate of the compound, which serves as headquarters of the paramilitary force Frontier Constabulary in the Bannu district of northwestern Khyber Phaktunkhwa province, provincial police chief Zulfiqar Hameed told reporters, hours after security personnel began an operation against the attackers.

Jabhatu Ansar al-Mahdi Khorasan (JAMK), a little-known militant group affiliated with Tehreek-e-Taliban Pakistan (TTP), claimed responsibility for the attack, the broadcaster Hum News reported.

Hameed told reporters earlier that five attackers were killed and seven other people were injured in the operation.