At least seven people including three suicide attackers were killed when Pakistan Taliban fighters stormed a police compound Friday in the port city of Karachi, said a provincial official.

"Four people were killed in the attack, including two policemen, one ranger, and one sanitary worker," Sindh government spokesman Murtaza Wahab Siddiqui told AFP, adding: "The operation has concluded with the killing of all three terrorists."

A spokesman for Tehreek-e-Taliban Pakistan claimed responsibility in a WhatsApp message to AFP.

"Our Mujahideen martyrs have attacked Karachi Police Office. More details to follow," he said.

Speaking on Samaa TV, Interior Minister Rana Sanaullah called the attackers "terrorists armed with grenades and other weapons" and said they fired at a gate with a rocket.

Prime Minister Shehbaz Sharif vowed Friday to stamp out the violence.

"Pakistan will not only uproot terrorism, but will kill the terrorists by bringing them to justice," he tweeted.

"This great nation is determined to end this evil forever."

- 'General threat' -

Earlier, Syed Murad Ali Shah, chief minister of Sindh province, told ARY news that security forces had focused on one main building seized by the attackers.

"It is a five-floor building. Our police and rangers have cleared the first three floors and approaching the fourth. The terrorists are still inside the building."

An AFP reporter near the scene saw dozens of ambulances and security vehicles arrive outside the compound.

Karachi is Pakistan's largest city, a sprawling metropolis of over 20 million people and the main trade gateway at its Arabian Sea port.

Low-level militancy, often targeting security checkpoints in the north and west, has been steadily rising since the Taliban seized control in neighbouring Afghanistan in August 2021.

The assaults are claimed mostly by the Pakistan Taliban, as well as the local chapter of the Islamic State, but separatists from Balochistan have struck over the years in Karachi, capital of the southern Sindh province.

Investigators blamed an affiliate of the Pakistan Taliban for the January blast at a mosque inside a police compound in Peshawar that killed more than 80 officers.

Tehreek-e-Taliban Pakistan share a common lineage and ideals with the Afghan Taliban.

Provinces around the country announced they were on high alert after the mosque attack, with checkpoints ramped up and extra security forces deployed.

"There's a general threat across the country but there was no specific threat to this place," Interior Minister Sanaullah said of Friday's Karachi attack.