Two staffers working for Virginia congressman Gerry Connolly were injured on Monday after being attacked by a man wielding a baseball bat.
Mr Connolly- a Democratic House representative, said that one of the victims was an intern on her first day on the job.
The attacker is in police custody and both staffers were treated in hospital for non-life threatening injuries.
About 7,500 threats against members of Congress were investigated in 2022.
In a statement posted to Twitter, Mr Connolly, who has served in the House since 2009, said that an individual had entered a district office in Virginia on Monday morning “and asked for me before committing an act of violence against two members of my staff.”
He added that the “thought that someone would take advantage of my staff’s accessibility to commit an act of violence is unconscionable and devastating.”
In an interview with CNN, Mr Connolly said that the assailant had struck a senior aide in the head with a metal bat and hit an intern – who was on her first day on the job – on the side. “He was filled with out-of-control rage,” Mr Connolly said.
In its own statement, US Capitol Police identified the suspect as 49-year-old Virginia resident Xuan Kha Tran Pham, who now faces one count of aggravated malicious wounding and one count of malicious wounding.
CBS, the BBC’s US partner, has reported that a man with the same name as the suspect last year filed a handwritten lawsuit against the CIA, seeking $29m for “brutally torturing” him “from the fourth dimension”. The justice department sought to dismiss the case earlier this year.
Mr Connally’s congressional district is mostly comprised of Fairfax County, a suburb of Washington DC in northern Virginia.
US Capitol Police, which are responsible for protecting members of Congress, have warned that threats against lawmakers have been rising in recent years.
In 2022, the force investigated 7,500 potential threats, though that was down from 9,600 in 2021. In 2017, the figure stood at less than 4,000.
“One of the biggest challenges we face today is dealing with the sheer increase in the number of threats against Members of Congress – approximately 400% over the past 6 years,” US Capitol Police Chief Tom Manger testified in April. “Over the course of the last year, the world has continuously changed, becoming more violent and uncertain.”
The issue of lawmaker safety was starkly highlighted in October, when Former House Speaker Nancy Pelosi’s husband Paul was seriously injured by a hammer-wielding suspect at the couple’s home in San Francisco. Speaker Pelosi was not at home at the time.