A person set themselves on fire outside the US Supreme Court on Friday, a spokeswoman said -- the second incident to raise alarm near the Capitol in Washington in a week.  

"At approximately 6:30 pm (2230 GMT), an individual went onto the plaza in front of the Supreme Court building and set themselves on fire," Supreme Court spokeswoman Patricia McCabe said in a statement.

"This is not a public safety issue," she said, adding that no one else was injured.  

No details about the person's health, identity or motives were provided.  

"A medical helicopter just landed near the Capitol for a medical emergency," US Capitol Police tweeted shortly after the incident.

The helicopter landed on the plaza and airlifted the person to a local hospital, McCabe said.  

The area was inaccessible and under investigation on Friday. 

The incident comes days after the Capitol was evacuated when authorities sounded a threat alarm over a harmless parachute stunt.

The alarm was triggered by a US Army parachute demonstration team's flyover at a nearby baseball stadium as part of a pre-game show.