At least two robberies were reported Sunday night in the downtown and Mall areas of the District, both involving about a dozen or more bicycle riders, according to D.C. police.

One robbery was reported near 7th and D streets NW, D.C. police tweeted at 8:46 p.m. In that incident, as many as 15 or 20 people appeared to be involved, the police were told.

The second robbery was reported near 15th Street and Constitution Avenue NW, police tweeted about 15 minutes later. The site is near the Washington Monument and the Ellipse. Police said a dozen or more youths appeared to be involved.

It was described as a snatch robbery, in which property is grabbed from the victim.

No injuries were reported.