A U.S. Capitol Police commander ordered the agency's SWAT team to stand down Monday morning as operators arrived at the gate of the Washington Navy Yard to confront the shooter, reports WUSA.

The agency's elite Containment and Emergency Response Team had answered a mutual-aid call from two Metro (D.C.) Police officers following the start of Aaron Alexis' rampage killing. The team is based a few blocks from the Navy Yard.

A Capitol Police watch commander "wouldn't let them go in and stop people from being slaughtered," one officer told the Washington TV station. The team was ordered back to the Capitol.

The Metro PD officers, including Officer Scott Williams, eventually entered the military facility and confronted Alexis. Officer Williams was wounded and Alexis was killed by police gunfire.