Four gunmen attacked the Pakistan Stock Exchange building by hurling hand grenades at security personnel in Pakistan's southern port city of Karachi on Monday morning, local media reported.
The gunmen reached at the site in a car and stormed the building during which several people were killed and injured.
All the attackers had been killed by police and security forces responding to the attack, said Faisal Edhi, head of the Edhi charity and ambulance service which serves the city.
There were around hundreds of people inside the building and security forces have kicked off a rescue operation bringing the situation under control.
As of 12:30 local time, 11 people were killed in the attack, including two civilians, four security guards at the Pakistan Stock Exchange and a policeman.
