A gunman opened fire at a White House security checkpoint on Saturday evening before being shot and killed in an exchange with Secret Service agents.

The suspect, identified in U.S. media as 21-year-old Nasire Best, was known to authorities and had a documented history of mental health issues.

The shooting began near Pennsylvania Avenue in Washington, D.C., causing panic as bystanders and reporters took cover nearby.

One bystander was wounded, but no Secret Service officers or White House protectees, including President Donald Trump, were injured, the BBC has reported.

Officials said the gunman used a revolver and was later pronounced dead at the hospital after being struck by return fire.