A bomb ripped through a Pakistani police patrol on Thursday, killing one policeman and wounding three others in the increasingly troubled southwestern city of Quetta, police said.
The device was detonated remotely when a police vehicle on a routine patrol passed along a road on the outskirts of Quetta, the capital of Baluchistan province, which suffers from Taliban, sectarian and separatist violence.
It was the second fatal attack on police in the city in two days.
"The bomb blast wounded four policemen and one of them died in hospital," senior police official Sikandar Tareen told AFP.
"It is not immediately clear who targeted the police," he said.
Another police official confirmed the attack and casualties.
There was no immediate claim of responsibility.
Police are frequently attacked in Baluchistan. On Tuesday, senior police official Shah Nawaz Khan was assassinated in Quetta in a drive-by shooting claimed by Al-Qaeda-linked militant group Lashkar-e-Jhangvi (LJ).
LJ has orchestrated violent attacks on Muslim minority Shiites and other police officials in Baluchistan say they have been threatened by the group.
On April 29, British aid worker Khalil Dale was found beheaded in Quetta, nearly four months after he was kidnapped in the city.
There has been no claim of responsibility for his murder.
Hundreds of people have been killed since separatist Baluch rebels rose up in 2004, demanding political autonomy and a greater share of profits from oil, gas and mineral resources in the region.