A female bicyclist was struck and killed Monday evening at down Washington D.C. by a security vehicle connected with the Nuclear Security Summit that being held in the city, local authorities said.?

The fatal accident occurred around 6 p.m. at the intersection of 12th Street and New York Avenue NW, just a few blocks away from the summit venue of Washington Convention Center and within the restricted area, said D.C. Fire and EMS officials.

Officials said the woman was hit by a five-ton military truck, when it was pulling into the intersection to block it off for a motorcade and failed to see the woman aboard her bicycle. D.C. police are on scene investigating the accident.

The U.S. capital has received an "immense level" of security service for the summit, which is believed to be the largest gathering of world leaders in the city in more than 60 years.

During the two-day summit hosted by President Barack Obama, leaders from 47 nations will discuss ways of securing nuclear materials from terrorists.

Security service has been beefed up inside and around the Washington Convention Center and the hotels where the world leaders are to stay.

Some major streets nearby have been separated with 10-foot-tall iron fences, while buses and subway trains have been ordered to skip the Mt. Vernon Station, which is close to the center, on Monday and Tuesday.

Major security agencies, including Federal Bureau of Investigation, Secret Service, Diplomatic Security Service and Coast Guard, will reportedly conduct "their operations in real-time using encrypted digital radios on existing frequencies."