Among the dead were five Shia Muslims, six activists of the Ahl-e-Sunnat Wal Jamaat, a front for the banned Sipah-e-Sahaba, a councillor of the PML-N and a worker of the Muttahida Qaumi Movement.
The Shias, including two doctors, were shot dead on Monday. The ASWJ members, including a scholar and a cleric, were gunned down in Defence, Mehmoodabad and Korangi areas, police said.
"These killings appear to be sectarian-related and retaliatory," a police official said.
A MQM worker was killed and his associate wounded in OrangiTown. The PML-N councillor was shot dead in his car by at Defence roundabout.
Two more persons were killed in a shooting at a hotel in Korangi Industrial Area. The trussed up body of a man who was shot dead was found in Lyari area.
Police also found the bodies of a couple, their throats slit, inside a water tank in Orangi Town while another body with torture marks was found in Baldia.
Police said the incidents of targeted killings had intensified since last night in different parts of Karachi.
The wave of violence came ahead of the month of Muharram, which begins on Wednesday.
The violence began even as army chief Gen Ashfaq Parvez Kayani arrived in Karachi to get a detailed briefing from security officials on operations carried out against criminal and militant elements in the city and security measures put in place for Muharram.
Karachi, the financial hub of Pakistan, has been hit hard in recent years by targeted killings, gang wars, kidnappings for ransom, extortion and terrorism.
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