A senior Pakistani police officer says gunmen opened fire on a former lawmaker outside his home in the southern port city of Karachi before fleeing.
Javed Odho says Ali Raza Abidi was critically wounded in Tuesday evening's attack and he later died at a hospital.
No one claimed responsibility for the attack, which drew condemnation from Prime Minister Imran Khan and several other opposition politicians.
Abidi was a former member of the National Assembly and his Muttahida Qaumi Movement party has urged the government to immediately trace and arrest his killers.
The Muttahida Qaumi Movement party represents the Urdu speaking population and its two factions have an uneasy relationship with each other.