According to police, the three men have already been identified and police personnel are actively searching for them.
The gunmen broke into actress Sumbul's house last evening and opened fire at her when she refused to accompany them to a private event. They fled the scene after killing her, Dawn reported.
The singer succumbed to her injuries before reaching the nearby Mardan Medical Complex. The body was handed over to the family after postmortem.
Sources said one of the accused, Naeem, was a former employee of police department, while the other, Jehangir, was the former husband of slain Pashto singer Ghazala Javed.
Jehangir was handed down death sentence on two counts and Rs 70 million fine by the Swat district and sessions judge in December 2013 in the killing case of Ghazala and her father Javed Khan. However, he was acquitted by the Peshawar High Court in May 2014 after he reached a compromise with Ghazala's family.