Reports of a helicopter landing on the National Mall this afternoon:
Very scary if true. This tweeter says she saw it happen:
We will continue to monitor this situation and update with developments.
Reuters reporter Myles Miller:
More from on-scene tweeter Vanessa Sink:
NBC Nightly News reports that the man was found conscious and breathing:
Disturbing tweet from a local NBC reporter:
Another on-scene tweet:
The man did not survive his injuries.