Security forces killed four gunmen who attempted to storm the Pakistan Stock Exchange building in Karachi on Monday. Four security guards, a police sub-inspector and a civilian were also killed in the attack, The Dawn reported. Three police officials have been injured, it further said.

The gunmen, according to The Dawn, stepped out of a vehicle and lobbed grenades before entering the stock exchange premises. AK-47 rifles, hand grenades, magazines and other explosive material have been recovered, the police said, adding that the equipment indicated that they had come for a long siege.

The building, which is in a high-security zone, also houses the head offices of many private banks. Karachi police chief Ghulam Nabi Memon told Reuters that they exchanged gunfire with security personnel. “The situation is still unfolding and management, with the help of security forces, is managing the security and controlling the situation,” the Pakistan Stock Exchange (PSX) said on Twitter. There was no immediate claim of responsibility.