At least three people were killed and 15 others wounded on Thursday after a bomb hit a Pakistani navy bus in the restive southern port city of Karachi, in the third such attack this week.
"A bomb planted on a roadside exploded when a Pakistan navy bus was passing by," provincial government official Sharfuddin Memon told AFP.
"A pedestrian was killed and 15 others were wounded," Memon said of the attack which took place in the city's busy Faisal avenue.
Naval officials said that a female doctor and a naval officer also died in the attack and nine other naval officials were wounded.
"One lady doctor and one officer were martyred in the attack and nine other officials were wounded in the bomb blast," a senior naval official told AFP.
Two security officials confirmed the attack.
Bomb attacks hit two buses carrying Pakistani navy officials in Karachi Tuesday, killing four people in the latest sign of rampant insecurity in a nation key to US hopes of winning its fight against the Taliban in Afghanistan.