Updated

Dozens of gang members angered over the killing of one of their leaders opened fire on passers-by outside a market Wednesday in southern Pakistan, killing 15 people, police said.

The gunmen used machine guns and grenades in the attack that wounded more than 40 people in the Lyari neighborhood of Karachi, the capital of southern Sindh province, senior police officer Shah Nawaz said.

Nawaz said a notorious gang was behind the attack, and a massive search was underway Wednesday night to find and arrest all those who had killed "innocent women, children and men."

"They will not go unpunished," he said.

Another police officer, Abdul Khaliq Sheikh, said police and paramilitary Rangers chased the gunmen and killed eight in a gun battle. He said supporters of a gang leader killed overnight in a shootout with police were behind the violence.

Television footage from the scene showed ambulances taking the wounded to hospitals.

Karachi is the largest city in Pakistan and home to various criminal gangs and militant groups.

Lyari is considered one of the city's more dangerous neighborhoods. Rival gangs often battle each other there. A January report by the International Crisis Group said gang members in Lyari operate like warlords and inter-gang warfare has included the use of mortars and other heavy weapons.

Hundreds of people have been killed in Lyari since 2009, and periodic operations by the paramilitary Rangers and police result in days of armed clashes, disrupting civilian life but not ending the violence, the report said.