Baloch separatists opened fire and hurled a grenade at the Pakistan Stock Exchange in Karachi on Monday, authorities said.
Four security guards, a police officer and a bystander were killed in the melee, while local police chief Ghulam Nabi Memon said all four assailants were also dead.
“Police have recovered modern automatic weapons and explosive materials from the terrorists,” Karachi police said in a statement.
The Balochistan Liberation Army (BLA) later claimed responsibility in a message.
The separatists have carried out a string of high-profile attacks across the country in recent years – including in the southern port city.
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 and Chinese workers in Pakistan multiple times in recent years, including during a brazen daylight attack on Bejing’s consulate in Karachi which killed four people in 2018.
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.
The US State Department last year designated the BLA as a global terrorist group, making it a crime for anyone in the US to assist the militants and freezing any US assets they may have.
Following Monday’s attack, Pakistani authorities vowed to strike back against any group found responsible for the onslaught, promising to dismantle their networks and destroy their bases.