The man, identified as Tariq Jatoi, had ordered Samina Samoon to stand up while singing but when she could not get up due to her pregnancy he shot her dead, said Abdullah Sheikh, the Deputy Inspector-General of Police (DIG).
She was rushed to a nearby hospital but she succumbed to her injuries.
The weapon used to murder the singer was recovered, Geo TV quoted the DIG as saying.
An FIR has been filed and a medical test of the accused ordered.
The police said the singer's husband filed a double murder report because of the unborn child.
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