At least six people were killed and several injured, including three police officials, as unidentified gunmen attacked the Pakistani Stock Exchange building in Karachi on Monday, reported Dawn. The security forces killed four attackers who attempted to storm the building and are on the lookout for more assailants.

“Four attackers have been killed, they had come in a silver Corolla car,” Karachi police chief Ghulam Nabi Memon told Reuters. The gunmen tried to enter the building around 10 am. Before that they lobbed grenades and started shooting. The building is in a high security zone and houses the head offices of many private banks.

Weapons and hand grenades have been recovered from the attackers. The security forces are examining a “suspected car” outside the building. No group has claimed responsibility for the attack yet.

Among those killed are a sub inspector, four security guards and a civilian. The number of casualties is likely to increase, according to Dawn.

Sindh Governor Imran Ismail condemned the incident. “Have instructed the IG & security agencies to ensure that the perpetrators are caught alive & their handlers are accorded exemplary punishments,” he tweeted. “We shall protect Sindh at all costs.”

The attack came more than a week after one person was killed and eight injured in a grenade attack outside a government welfare office in Karachi. In 2018, militants had carried out an attack on the Chinese consulate in Karachi in which four people died.