Chaudhry Zulfikar was shot at least 13 times as he drove to court in the capital Islamabad.
He then lost control of his car, which hit a woman passer-by and killed her, police said.
Mr Zulfikar was also prosecuting militants linked to the 2008 terror attack in the Indian city of Mumbai.
Although the motive for the killing was unclear, the prosecutor's involvement in the two high-profile cases is likely to be scrutinised closely.
More top news
Clear and cooler conditions to the south and east with lows into single figures.
Police have arrested three teenagers and a man following the shooting of a three-year-old girl with an air gun.
Police have released new images of the site of the fatal crash near Shoreham Airshow in which at least 11 people died.