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
The shocking video of Laquan McDonald being killed brings the debate about racism in the US criminal justice system centre stage once more.
A video of a white police officer shooting dead a black teenager has been released by authorities in Chicago.
Cold in the wind