U.S. Capitol Police investigating possible active shooter

(Washington, DC)  --  U.S. Capitol police are investigating a possible active shooter in and around the Senate Office Building.  

Officials said they received what they called a "concerning 911 call."  

Police advised those in the Senate Building to shelter in place.  

There have been no confirmed reports of gunshots.  

Congress is currently not in session.  

The call reportedly concerns a mental health crisis.