A massive manhunt entered a second day on Sunday in Minnesota for the gunman who killed a Democratic state lawmaker while posing as a police officer, a crime that Governor Tim Walz characterised as a "politically motivated assassination".
The suspect, whom police identified as Vance Luther Boelter, 57, fled on foot when officers confronted him at the Brooklyn Park home of former Minnesota House Speaker Melissa Hortman and her husband, Mark, who were both killed.
The gunman earlier had shot and wounded another Democratic lawmaker, state Senator John Hoffman, and his wife Yvette at their home a few miles away, authorities said.
Minnesota US Senator Amy Klobuchar, a Democrat, said on Sunday morning that authorities believe the suspect is still in the Midwest, adding that an alert had been put out in neighbouring South Dakota.
"Clearly, this is politically motivated," she said, noting that the state's entire congressional delegation - Republicans and Democrats - issued a shared statement condemning the shootings.
The suspect left behind a vehicle outside Hortman's house in suburban Minneapolis that resembled a police SUV, including flashing lights, and contained a "manifesto" and a target list of other politicians and institutions, officials said.
Authorities had not publicly identified a specific motive as of Saturday evening.
Boelter had been appointed in 2016 by Walz' predecessor to a state advisory board, where he served alongside Hoffman, according to state records. Authorities said they were not certain yet whether the two had any meaningful interactions.
"There's certainly some overlap with some public meetings, I will say, with Senator Hoffman and the individual," Minnesota Bureau of Criminal Apprehension Superintendent Drew Evans told reporters on Saturday. "But we don't know the nature of the relationship or if they actually knew each other."
ABC News, citing law enforcement officials, reported the list of targets featured dozens of Minnesota Democrats, including Walz, who was also the Democratic vice presidential candidate last year.
The killing was the latest in a series of high-profile episodes of political violence, including the attack on former Democratic US House Speaker Nancy Pelosi's husband in 2022, the attempted assassination of Donald Trump during last year's presidential campaign and an arson attack at Pennsylvania Governor Josh Shapiro's house in April.
Republican and Democratic politicians across the country reacted with shock and horror and issued calls to tone down increasingly heated political rhetoric.
Klobuchar said she had seen both Hortman and Hoffman at a political dinner on Friday, just hours before they were shot.

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