Three paramilitary personnel were killed and four more injured when a vehicle of the Pakistan Rangers was hit by a roadside bomb in the southern port city of Karachi on Friday.
The blast occurred in Safoora Goth area of Karachi at 7.25 am.
The powerful bomb packed with ball bearings was hidden in a pile of earth beside a road, Deputy Inspector General of Police Akram Naeem said.
Seven Pakistan Rangers personnel were injured by the blast. Three of them succumbed to their injuries in a military hospital.
The other injured personnel were out of danger, officials said.
Naeem said the paramilitary personnel were the target of the attack.
Footage on television showed the vehicle was peppered by shrapnel and its windows blown out.
Security forces cordoned off the area and conducted a search.
There was no claim of responsibility for the attack.
The Tehrik-e-Taliban Pakistan and several other extremist groups are active in Karachi and have carried out major attacks on security and intelligence officers in recent months.