Sunday's heavy police presence in downtown D.C. is still a mystery.
Officers from D.C. Police, Park Police, and Homeland Security converged near the L'Enfant Plaza Metro station around 4:30 p.m. Sunday.
Streets were shut down for about 5 hours causing problems for drivers and tourists who couldn't get back to their hotel.
Police haven't given any official explanation about what happened
Witnesses and a source tell FOX 5 that the incident started with a call about someone possibly having a pipe bomb and a hostage.