A bomb tore through a Pakistan security forces' vehicle on Thursday, killing 11 people and wounding dozens more in a crowded part of the southwestern city of Quetta, officials said.
"Frontier Corps (paramilitary) personnel were the target because the bomb was planted underneath their vehicle," said senior police investigator Hamid Shakeel.
It was not immediately clear who carried out the attack.
Quetta is the capital of the province of Baluchistan, one of the most deprived parts of Pakistan, which suffers from Islamist militancy, a separatist insurgency and sectarian violence.
"According to our information, 11 people were killed and 27 injured in the blast. We will be able to tell you after some time what kind of device it was, but it was a crowded place," said Quetta police chief Mir Zubair Mehmood.
Bomb disposal official Abdul Razzaq said the bomb, packed with 20 to 25 kilograms (44 to 55 pounds) of explosives, was detonated by remote control.
TV stations broadcast harrowing images of casualties being stretchered from the scene, heavily damaged vehicles and survivors picking through the debris.
It was the worst attack in Baluchistan since a car bomb killed at least 19 Shiite Muslim pilgrims en route to Iran in Mastung district, some 30 kilometres (18 miles) south of Quetta, on December 30.
Shiites make up around 20 percent of Pakistan's 180-million strong population and rights activists say they are increasingly being targeted by extremist Sunni factions.
Baluch rebels rose up in 2004, demanding political autonomy and a greater share of profits from the region's wealth of natural mineral, oil and gas deposits.
The province borders Afghanistan and Iran.