According to sources, the number of terrorists involved in the attack is not confirmed.
Heavily-armed Pakistani Taliban militants on Friday stormed the Karachi Police chief's office in the country's most populous city, sparking gunfire that killed two rebels and two others, the latest brazen assault on security forces amid an uptick in terror attacks across the country.
The attack took place around 7:10 pm local time.
A spokesperson of the Karachi Police confirmed in a statement that the Karachi police chief's head office had come under attack.
“Firing is going on,” the statement said.
Karachi Police chief Javed Odho also confirmed in a tweet that his office was under attack but said the security forces had responded strongly.
Senior Police Official, DIG South Irfan Baloch said during the standoff, two of the rebels, a policeman and a civilian were killed.
He said six others, including four policemen, were also injured.
“Some of the militants entered via the backside of the building while two entered from the main gate wearing police uniforms," he said.
He said the police have surrounded the terrorists inside the building and one floor of the building had been cleared.
“There are around six terrorists still inside the building," he said.
The dreaded Pakistani Taliban terror group has claimed responsibility for the attack.
The terrorists first threw half a dozen hand grenades into the main compound of the Karachi Police Chief's office building and then entered the premises.
“Heavy firing is going on between paramilitary rangers, police and the attackers. All mobile vans in the district and area have been summoned urgently to the spot to surround the attackers,” one police source said.
The Karachi Police chief's office is located near the main artery road of Karachi which goes from downtown to the airport.
Pakistan has witnessed a surge in militant attacks since November when Pakistani Taliban ended a monthslong cease-fire with the government.
Last month, a Taliban suicide bomber blew himself up in a mosque packed with worshippers during afternoon prayers in the high-security zone in Pakistan's restive northwestern Peshawar city, killing over 100 people, mostly policemen.
(Except for the headline, this story has not been edited by NDTV staff and is published from a syndicated feed.)