At least six people were killed when gunmen attacked the Pakistan Stock Exchange in Karachi on Monday, with a policeman among the dead after the assailants opened fire and hurled a grenade at the trading floor, police said.

The assault was claimed by ethnic Baloch separatists who have hit a string of high-profile targets across the country in recent years, including in the southern port city.

Four security guards, a police officer and a bystander were killed in the melee, while local police chief Ghulam Nabi Memon confirmed that all four attackers were also dead.

"Police have recovered modern automatic weapons and explosive materials from the terrorists," Karachi police said in a statement.

Pakistan Stock Exchange Shooting
The assault in Karachi appears to the be the latest in a string of attacks masterminded by ethnic Baloch separatists Photo: AFP / Rizwan TABASSUM

Security forces had secured the area with at least two gunmen laying in a pool of blood near the scene of the attack.

The Balochistan Liberation Army (BLA) later claimed responsibility in a message sent to AFP, saying an elite unit of fighters had carried out the assault.

The BLA is one of several insurgent groups fighting primarily in Pakistan's southwestern Balochistan province, which has been rocked by separatist, Islamist and sectarian violence for years.

The group has targeted infrastructure projects along with Chinese workers in Pakistan multiple times in recent years, including during a brazen daylight attack on the Chinese consulate in Karachi which killed four people in 2018.

Karachi
Karachi was once a hotspot for crime and violence Photo: AFP / Asif HASSAN

In May last year, the BLA attacked a luxury hotel near the Afghan border at Gwadar, where a port development is the flagship project of a multi-billion dollar national infrastructure project funded by China.

Karachi was once a hotspot for crime and violence, with heavily armed groups tied to politicians frequently gunning down opponents and launching attacks on residential areas.

But the situation has largely stabilised in recent years following operations by security agencies against armed political outfits and Islamist militants.

The operations were coupled with a series of large-scale military offensives targeting homegrown insurgents as well as Taliban and Al-Qaeda-linked militants -- often based near the lawless border with Afghanistan.

Militant groups still retain the ability to launch periodic attacks in many rural areas of the country.

Monday's attack comes a week after a grenade was thrown at a line of people waiting outside a government welfare office in the city, killing one and injuring eight others, according to a statement from municipal authorities.

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