A police official, his driver and his guard were gunned down by unidentified assailants on GT Road in Sheikhupura district on Monday.
The Station House Officer (SHO) at Lahore's Rang Mahal police station, Zahid Mehmood, was injured in firing and was being transported to the hospital when he succumbed to his wounds.
His driver and guard died on the spot, District Police Officer (DPO) Sheikhupura Jahanzeb Nazir Khan told DawnNewsTV.
Mehmood had been travelling from his home in Sheikhupura's Murdike area to Lahore when gunmen opened fire on his car on GT Road, the DPO said.
The assailants fled the site of the attack. Police have erected district-wide blockades and initiated a search operation in an attempt to arrest the suspected attackers.