The first crash happened some time before 9 a.m. near the Polo Fields south of the National Mall, in the 1900 block of Ohio Drive SW.
The bicyclist in that crash flown to an area hospital with serious injuries. U.S. Park Police and D.C. Fire and EMS responded to the scene.
The second crash happened shortly before 9 a.m., when a bicyclist was struck in the southbound lanes of the Baltimore-Washington Parkway near the exit for Route 197.
There is no word yet on that bicyclist's condition.
Both driver of the striking vehicles remained on the scene.
The BW Parkway is not a good place to ride (and it's illegal). But if you're trying to go north-south in that area, there aren't many good options.
Update: NBC Adds - An earlier version of this story also referenced a collision between a bicyclist and a driver on the Baltimore-Washington Parkway near the exit for Route 197.
However, when police arrived, they found neither the driver or the bicyclist. They then left the scene.