A manhunt is under way in Minnesota after two state lawmakers were targeted and one of them killed on Saturday morning in what Governor Tim Walz called an "act of targeted political violence".

Melissa Hortman, 55, a Democrat, and her husband were killed in Brooklyn Park, a city near Minneapolis.

John Hoffman, 60, also a Democrat, and his wife were shot several times at their home about 15km (nine miles) away in a related attack. He is out of surgery and stable.

A search is on for the suspect who police say was impersonating an officer. He has been named as Vance Luther Boelter, 57 and there is a $50,000 reward for information leading to his arrest.

The roads around the scene in suburban Brooklyn Park were quiet on Saturday night, with a discreet police presence and little sign locally of the manhunt for the suspect.