The accident happened around 6 p.m. at the intersection of 12th Street and New York Avenue, NW.
The vehicle that collided with the woman on the bike was a five-ton truck with the D.C. National Guard.
"It was moving forward to block as a procession was coming through," said Major Gen. Errol Schwartz of the D.C. Guard.
The woman has been identified as Constance Holden, 68, of the Mount Pleasant neighborhood in Northwest. Holden, known to friends and colleagues as "Tancy," had just left the American Association for the Advancement of Science headquarters when the incident happened.
According to AAAS, Holden had been on the staff of Science magazine since 1970. An award-winning reporter, Holden was highly regarded for her comprehensive coverage of the biological and genetic bases for human behavior, according to AAAS, and edited the journal’s weekly “Random Samples” page, a compendium of newsworthy scientific developments.
“(She) was held in very high esteem and with great affection by both those people with whom she worked and our readers," said Alan I. Leshner, chief executive officer of AAAS and executive publisher of Science. "This is a terrible loss both personally and professionally for so many on our staff who knew her well.”
Holden also was an painter. Her work can be found at the Web site HoldenPortraits.com. Her colleagues said she was planning a show of her paintings at her home on Sunday.
It’s not clear yet who was at fault in Monday's incident, according to the chief commander of the D.C. Guard.
“We will look at the video to make sure the pedestrian didn’t roll into the path of the truck as it was moving,” Schwartz said.
The National Guard truck had a human escort walking alongside the vehicle to guide it through crowds.
Although the driver of the vehicle was assigned to a motorcade security route for dignitaries attending the Nuclear Security Summit, police said he was not actively part of a motorcade at the time of the collision.
Police are investigating the incident.
The Nuclear Security Summit continues Tuesday with more road closures. Click here for a complete list, and to view real-time traffic maps.