A leading Pakistani human rights activist has been killed in a drive-by shooting in Karachi after hosting a talk on allegations of torture in the province of Balochistan.
Sabeen Mahmud was shot dead as she walked home with her mother, who was also attacked.
Ms Mahmud had been the subject of death threats before.
Tributes were paid to her on social media as soon as news of her death emerged
Ms Mahmud was a director of the charity The Second Floor, also known as T2F.
T2F regularly holds seminars on human rights issues. It houses a cafe and book shop where Karachi's liberal activists and students can meet.
The seminar on torture in Balochistan was held at T2F, having been cancelled by university authorities in Lahore, where it had been due to take place in the last few weeks.
Taliban militants, Baloch separatists and other groups fight in Balochistan, which borders Iran.
Shortly after leaving the event, Ms Mahmud and her mother were shot. Pakistan's Dawn newspaper reported that Ms Mahmud died on her way to hospital, and that she had been shot five times.
Dawn reported that her mother is in a critical condition in hospital.
Within an hour of the attack, tributes had started appearing on social media.
Horrible news! Sabeen Mahmud of T2F shot dead a couple of hours after organising 'Unsilencing Balochistan' there pic.twitter.com/tGIrPNw6Sq— Bilal Farooqi (@bilalfqi) April 24, 2015
Our wonderful, friend heroine and fallen soldier @sabeen May you rest in peace but we will not until your killers are found and prosecuted— Fifi Haroon (@fifiharoon) April 24, 2015
Among the tributes was one from Siraj ul Haq, the head of the conservative Islamist group Jamaat-e-Islami, who tweeted: "Murder of Sabeen Mahmud is shocking & horrific. It is extremely condemnable, indeed coward of them to target a woman."
No group has yet said it carried out the attack, though Ms Mahmud is believed to have been the subject of threats by the Pakistani Taliban in the past.
Me Mahmud set up T2F having already established a charity, PeaceNiche, in Karachi. She said she "maxed out seven credit cards" to keep the centre going.
She also helped promote the importance of learning computer skills among Pakistani youth, and hosted hundreds of events at T2F.
In a profile in a Pakistani media magazine in 2013, Ms Mahmud was asked what her superpower would be. She answered: "I'd like to wave my magic wand and de-weaponise Karachi."