WASHINGTON, United States  (AFP) — Police and FBI agents waged a huge manhunt Sunday for a gunman who killed a Democratic state lawmaker and her husband in Minnesota in what officials called a politically motivated attack.

As America reeled from its latest spasm of political violence, lawmakers called for a return to civility in political discourse that has been overheated and angry for years.

Authorities searched for a man identified as Vance Boelter, 57, who also allegedly shot and wounded another lawmaker and his wife early Saturday in the northern state bordering Canada.

Officials said Boelter impersonated a police officer as he came to the homes of these couples near Minneapolis and shot them, and that officers found a manifesto and a list of other lawmakers and potential targets in his car.

Boelter fled on foot after exchanging gunfire with officers after the second shooting.

Officials have issued security alerts in South Dakota and other states as the hunt proceeds, United States (US) Senator Amy Klobuchar of Minnesota said Sunday as she mourned her slain friend, Democratic state representative Melissa Hortman.

“I am concerned about all our political leaders, political organisations,” she said.

“It was politically motivated, and there clearly was some throughline with abortion because of the groups that were on the list, and other things that I’ve heard were in this manifesto. So that was one of his motivations.”

As speaker of the Minnesota House of Representatives, Hortman was committed to legislation that protected reproductive rights in the state, local media reported.

America is bitterly divided politically as President Donald Trump embarks on his second term and routinely insults his opponents. Political violence is becoming more and more common.

Trump himself survived an assassination attempt last year. An assailant with a hammer attacked the husband of then US House speaker Nancy Pelosi in 2022. And Pennsylvania Governor Josh Shapiro’s house was set on fire this year.

“We need to bring the tone down, Klobuchar said on CNN.

US Senator Rand Paul of Kentucky, himself attacked by a neighbor in 2017, told NBC “nothing brings us together more than, you know, mourning for somebody else who’s in political life, Republican or Democrats.”

On Saturday the FBI released a photo that appears to show Boelter wearing a mask as he stands outside the home of one of the lawmakers.

It is offering a $50,000 reward for information leading to his arrest and conviction.

The shootings came on the day a dramatic split screen showed America divided: hundreds of thousands of protesters across the country took to the streets to rally against Trump as the president presided over a big military parade in Washington — a rare spectacle criticised as seeking to glorify him.

Trump has condemned the killing of Hortman and her husband Mark and the wounding of state Senator John Hoffman and his wife Yvette.

In a conversation Sunday with ABC News, Trump was asked if he planned to call Minnesota Governor Tim Walz, who was Kamala Harris’s running mate in the election Trump won last year.

“Well, it’s a terrible thing. I think he’s a terrible governor. I think he’s a grossly incompetent person,” the president said. “But I may, I may call him, I may call other people too.”