PESHAWAR, Pakistan (AP) — Pakistani security forces raided a militant hideout in the northwestern city of Peshawar on Tuesday, triggering an 18-hour shootout in which a police officer and all five suspected militants at the site were killed, officials said.

Police and commando units surrounded the house in Peshawar on Monday night, asking the suspects inside to surrender. Instead, they opened fire on the security forces, setting off clashes, said Shaukat Yousafzai, a government spokesman in Khyber Pakhtunkhwa province.

Police said the suspects also threw grenades, which killed the officer.

The operation lasted 18 hours. Security forces found explosives in the basement of the house, but no additional suspect. According to Yousafzai, the suspects had been living in the house for the past two weeks, plotting to target government and security forces.

He added that the authorities were trying to determine the identities and nationalities of the slain militants.

Peshawar is the provincial capital in Khyber Pakhtunkhwa, which borders Afghanistan and which has witnessed dozens of militant attacks in recent years, most claimed by the Pakistani Taliban.