Unidentified gunmen opened fire on a police vehicle on Thursday, killing three police officers in Pakistan's biggest city Karachi.
Authorities said a police vehicle was on routine patrol in the centre of the city when it came under fire.
The policemen were rushed to a nearby hospital, where they died.
The motive behind the killings was unclear, and police said they're investigating the attack.
Karachi has a long history of violence, and ethnic, religious and sectarian disputes can often explode into battles engulfing entire neighbourhoods.
More than two dozen people have been killed in the city over the past week alone.
Travis Brecher, Reuters
