A violent clash between two rival gangs left 12 people including four women dead and over 40 others injured in Pakistan's southern port city of Karachi on Wednesday morning, local media reported. Urdu TV channel Express said that the gang war in Jhat Patt market in Layari area of the city took place after one gang kidnapped a member of the other on Tuesday night. Eyewitnesses said that they heard six to seven small explosions in the market area. The grenade attack followed by a fierce exchange of fire between the armed groups left 12 people dead and over 40 others including four kids and several women injured. The women and kids were shopping in the area and some kids were going to school when the attack happened, police said. Police cordoned off the area for investigations. Layari is a restive area in Karachi, the capital of the country ' s southern Sindh province, which is considered a hub of extortion mafia.