Shortly after 1pm local time, a man in a blue Sedan car rammed his vehicle into the North Barricade at the US Capitol striking two USCP officers.
He then left the vehicle and ran towards the officers with a knife when he was shot by one of them.
All three men involved were taken to hospital where one of the officers and the suspect died from their injuries.
A statement from US Capitol Police said: “We are devastated to share the news that one of our officers involved in this afternoon's incident passed away.
"USCP is working to identify the officer’s next of kin before it releases additional information.”
It added: “One USPC officer was transported by USCP cruiser to hospital. The second USCP officer was transported by DC Fire and EMS. The suspect was also transported by DC Fire and EMS to the hospital where he succumbed to injuries around 1.30pm.”
Investigations into the incident are ongoing.
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