The bodies had mark of torture besides bullet wounds and they were dumped in Ijtima ground of Manghopir, an area known as hub of Taliban militants and criminals involved in extortion, land grabbing and drugs.
Ahmad Tarin, a local police told PTI, that the legs and hands of all were tied with ropes.
"Three of them have been identified as Taliban militants from Swat (in the northwest). The other four are not known and their bodies were sent to Abbasi Shaheed Hospital," Tarin said.
It is believed that these killings could be linked to the separation of Khan Sajna group from the Taliban led by Maulana Fazlullah.
Sajna controls most of South Waziristan and parted ways with Fazlullah over the issue of peace talks with the government.
His followers in Karachi already killed dozens of rivals.