Members of Congress were among the first to issue reports of shots being fired outside the Capitol, sending out Twitter messages and reassurances of their own safety. 

Sen. Claire McCaskillClaire McCaskillSenators question need for HHS cyber office Overnight Cybersecurity: Obama DHS chief defends Russian hack response | Trump huddles on grid security | Lawmakers warned about cyber threat to election systems We must protect our most vulnerable from financial fraudsters MORE (D-Mo.) was the first member to tweet.



Initial reports suggested the shooting happened on the House side of the Capitol, but the entire complex went on lockdown, Rep. Joaquin Castro (D-Texas) said.



Rep. Grace Meng (D-N.Y.) posted a picture of a police officer pointing a gun toward the outside of the Capitol. BuzzFeed reporter Kate Nocera first posted the photo.



Other members tweeted they were told to “shelter in place,” and that their staffs were safe.



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The House, which was in session, had to go into recess.



Multiple reports said a Capitol police officer had been shot, and was injured.



An alleged shooter was taken down, according to multiple reports.



Rep. Jared Polis (D-Colo.) tweeted the alert he received via text message.




But many lawmakers and congressional reporters said they didn’t know what was happening.