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WASHINGTON (Reuters) -A gunman posing as a police officer killed a senior Democratic Minnesota lawmaker and her husband on Saturday in an apparent “politically motivated assassination,” and wounded a second lawmaker and his spouse, Minnesota Governor Tim Walz said.

A major search was underway for the suspect, who fled on foot after firing at police, abandoning a vehicle in which officers found a “manifesto” listing other legislators and officials, law enforcement officials told a news conference.

President Donald Trump said he had been briefed on the “terrible shooting that took place in Minnesota, which appears to be a targeted attack against State Lawmakers.”

“Such horrific violence will not be tolerated in the United States of America. God Bless the great people of Minnesota, a truly great place!” he said in a statement.

Those killed were Democratic state assemblywoman Melissa Hortman, a former assembly speaker, and her husband, Mark, Walz and law enforcement officials told reporters.

Walz said that the gunman went to the Hortmans’ residence after shooting Senator John Hoffman and his wife, of Champlin, multiple times.

They underwent surgery, Walz said, adding that he was “cautiously optimistic” that they would survive “this assassination attempt.”

“This was an act of targeted political violence,” he said. “Peaceful discourse is the foundation of our democracy. We don’t settle our differences with violence or at gunpoint.”

Law enforcement authorities said the gunman was dressed as a police officer and escaped after exchanging fire with police who went to the Hortmans’ home.

(Reporting by Jonathan Landay, editing by Michelle Nichols and Diane Craft)