A text message has been sent to all staff in the Capitol building in Washington DC warning staff to stay inside the building.
A large presence of emergency services has been reported outside the building.
People inside cannot come in or out, and have been told to keep away from windows.
SUBSCRIBE to our YouTube channel for more videos: www.youtube.com/skynews
Follow us on Twitter: twitter.com/skynews
Like us on Facebook: www.facebook.com/skynews
Follow us on Instagram: www.instagram.com/skynews
For more content go to news.sky.com and download our apps:
Sky News videos are now available in Spanish here/Los video de Sky News están disponibles en español aquí www.youtube.com/channel/UCzG5BnqHO8oNlrPDW9CYJog