Dallas surgeon Brian Williams is running for Congress

A trauma surgeon who rose to prominence after treating Dallas police officers ambushed by a sniper in 2016 is running for Democrat Rep. Colin Allred's seat in Congress.

Why it matters: Brian Williams, an Air Force veteran who completed his medical residency at Harvard before working at Parkland Memorial Hospital, has a story and a message that could take him a long way in American politics.

The big picture: Running as a Democrat, Williams wants to help curb the country's epidemic of gun violence, he tells Axios. He's also concerned about unaffordable health care coverage and environmental issues, and says "reproductive rights are under attack."

Of note: Allred has announced that he's not seeking re-election and will instead run for Republican Sen. Ted Cruz's seat in 2024.

Flashback: Williams was in charge of Parkland's trauma room in July 2016, treating seven of the 16 people shot in the sniper attack downtown. Five officers died as a result of the shooting.

• Williams found himself at the center of a national conversation about race and policing.
• "I want the Dallas police officers to see me, a Black man. I support you. I will defend you. I will care for you. That doesn't mean I do not fear you," Williams said at a press conference at the time.

Between the lines: Williams says the shooting was the catalyst for his involvement in politics.

• "That was a transformative and defining moment in my life," he tells Axios.

• Since then he's pushed for gun safety on a national level, working as an adviser for Sen. Chris Murphy (D-Conn.) and former House Speaker Nancy Pelosi.

What they're saying: "I could only do so much inside the hospital, wearing a white coat with a scalpel," Williams says. "My work had to extend outside the hospital."

By the numbers: Williams has raised more than $360,000, according to his campaign's most recent Federal Election Commission filing.

Yes, but: State Rep. Julie Johnson, a Democrat from Farmers Branch — Williams' most high-profile opponent in the March primary — raised $410,000 in the same period.

What we're watching: With five candidates already vying for the Democratic nomination, and so much time before the primary, the field could get even more crowded.