Central District SSP, Muqadas Haider told Dawn online that four suspects riding on two motorcycles opened fire on Zaki, 40, while he was having dinner at a restaurant.
The activist was killed, while two others – journalist Rao Khalid and a bystander – were critically wounded in the attack.
A former journalist, Zaki was an active campaigner for human rights and was the editor of the website and Facebook page ‘Let Us Build Pakistan (LUBP)’ which claimed to “spread liberal religious views and condemned extremism in all forms”.
According to his Twitter profile, Zaki was the former head of current affairs for TV Channel News One, where he looked after infotainment and religious programming.
Zaki’s website Lubpak.com is currently blocked in Pakistan.
Zaki was last in the media limelight alongside activist Jibran Nasir in a campaign against Lal Masjid cleric Maulana Abdul Aziz for inciting hatred against Shia Muslims.
The campaigners had managed to get a case registered against Aziz.
Rights activist Sabeen Mahmud, who was also gunned down in Karachi, had taken part in the protest against Lal Masjid as well.