Thousands of people have disappeared from the province in recent years amid a government crackdown on nationalists and insurgent groups there. Activists blame the government for the disappearances, something authorities deny.
Qadeer Baluch, an activist who last year led a nearly 3,000-kilometer (1,900-mile) protest march across Pakistan to demand justice for the missing in Baluchistan, attended Mehmud's event Friday night. Baluch, known widely as Mama or "Uncle" in Urdu, hinted that the government could be involved in Mehmud's slaying.
"Everybody knows who killed her and why," Baluch told Pakistan's The Nation newspaper, without elaborating.
In a statement Saturday, Prime Minister Nawaz Sharif condemned Mehmud's killing and ordered an investigation into the attack. The U.S. Embassy in Islamabad also condemned Mehmud's slaying and offered condolences to her loved ones.
Mehmud was "a courageous voice of the Pakistani people and her death represents a great loss," it said.
Mahmud, a well-known activist who also ran a small tech company, hosted poetry readings, computer workshops and other events at The Second Floor. She continued to live in Karachi, Pakistan's southern port city, even while acknowledging the danger from insurgent groups and criminals operating there.
"Fear is just a line in your head," Mahmud told Wired magazine in 2013. "You can choose what side of that line you want to be on."
Associated Press writer Munir Ahmed in Islamabad contributed to this report.