KARACHI: Gunfire erupted outside of police headquarters in Pakistan’s largest city on Friday, as security forces rushed to stave off what appeared to be a bold attack in the heart of Karachi, police and officials said.

Two of the attackers were killed and at least one security official wounded, said Ghulam Nabi Memon, police chief for the Sindh province where Karachi is located and a venue of the country's largest cricket tournament,.

City police chief Javed Alam Odho confirmed that an attack was ongoing and said police and paramilitary troops were responding.

It wasn’t clear who was behind the assault on the police headquarters, the police chief added.

Police snipers took up positions near the station. There were no immediate reports of deaths.

"Can't exactly tell how many terrorists have entered but there are at least more than five," Deputy Inspector General Irfan Baloch told Reuters.

Cricket matches

The station houses offices of the city's most senior police. Baloch said there could have been up to 30 police at the station at the time of the attack.

Overseas cricket players are competing in the Pakistan Super League, and Karachi is one of three host cities. There is a game scheduled for Saturday.

The police station is located along the route to the stadium and the hotel is a few kilometres away.

The police station is located along the route to the stadium and the hotel is a few kilometres away.

Top teams shunned Pakistan for years after six policemen and two civilians were killed in a 2009 attack on a bus carrying the Sri Lankan cricket team in Lahore.

Police sealed off traffic on the main thoroughfare through the city and heavy contingents of security forces, including paramilitary soldiers, had arrived at the scene.

Odho provided no further details and TV footage showed officers surrounding the city’s central police station. Residents said they also heard the sound of explosions amid the clashes.

Pakistan’s Interior Minister Rana Sanaullah Khan said five or six militants were involved in the attack and threw hand grenades as they tried to force their way into the police headquarters.

Sharjeel Memon, the Sindh province’s spokesman, said the attackers had been surrounded although shooting and clashes were still underway.

No group has so far claimed the attack.

Pakistan has witnessed a surge in militant attacks since November when Pakistani Taliban ended a monthslong ceasefire with the government.