Mohammad Azeem, an official at the charity Eddie Rescue Center, said police and security officials have confirmed death.
Rescue and paramilitary security personnel are on the scene, Azeem said.
According to CNN’s affiliate Geographic News, the video shows security and roadblocks outside the Karachi Stock Exchange.
Abid Ali, director of the Pakistan Stock Exchange, said in an Earth News briefing that four attackers entered the compound and started shooting, but were killed by security forces.
Ali said: “Four attackers came in from the parking lot. They threw a grenade at the main entrance of the KSE (stock exchange) and then opened fire at will.”
“The attacker was wearing a uniform that looked like a police uniform. All four people were killed and the situation is currently under control.”
The tweet wrote: “Once the situation is under control and we know more details, we will issue a more detailed statement in due course. At present, the shooting has stopped and reinforcement work is in place.”
The Pakistani stock exchange administration issued a message saying that “commando” had entered the compound and “four terrorists” had died.
The government told the workers in the building to stay on the higher floors. “The rangers will sort out the compound and let everyone leave in an orderly manner.”
Karachi’s Pakistan Stock Exchange is the largest in the country. It is located in the city’s financial center, where all major banking and financial services are located, and usually has a large number of security departments.
This is a developing story.