In what appeared to be a sectarian attack, unidentified gunmen on Sunday evening ambushed a bus carrying Pakistani police trainees, killing 11 and leaving nine injured in the southwest city of Quetta in Baluchistan province.
Two motorcycle-borne assailants carrying Kalashnikovs indiscriminately fired on the bus in Saryab Road in Quetta, Raja Ishtiaq, the officer-in-charge of the local police station said.
Police suspect it to be a sectarian attack as all the cadets were from the Shiite sect.
Twenty-five police recruits, mainly hailing from the province, were returning to their Police Training School after a weekly holiday, when the incident took place, Senior Superintendent Police (Quetta) Rehmatullah Niazi told reporters.
Some of the injured trainees are in serious condition, he said adding five policemen escaped unhurt.
It is one of the worst attacks on the Pakistani police in recent times.
Baluchistan, the home province of Prime Minister Mir Zafarullah Khan Jamali, shares a border with Afghanistan.
Police do not rule out the involvement of local tribes, who often clash with security forces to assert their rights.