James Hodgkinson, the 66-year-old man who shot and injured a US Congressman yesterday had been in the Alexandria (US) area since March and was living out of his vehicle.

Hodgkinson, who had posted angry messages against President Donald Trump and other Republicans on social media, opened fire on Republican lawmakers practising for a charity baseball game, wounding a senior US House member and three other people.

The suspect fired repeatedly at the men playing on a baseball field in suburban Alexandria, Virginia, near Washington D.C.

He was wounded in a gunfight with Capitol Hill police who were at the scene, and the police confirmed he was dead.

Steve Scalise, the No. 3 Republican in the House of Representatives, was shot in the hip. He was tended to by fellow lawmakers including Brad Wenstrup, a congressman who is a physician, before being transported to a hospital, where he was listed in critical condition.

Also wounded were one current congressional aide and one former aide who now works as a lobbyist, officials said. One Capitol Hill police officer suffered a gunshot wound and another officer twisted an ankle.

While police and the Federal Bureau of Investigation said it was too early to determine whether it was a deliberate political attack, the shooting intensified concerns about the sharp divide and bitter rhetoric in US politics.