Nelson was struck in the upper body and flown to a Baltimore hospital, where she died hours later, police said.
Another woman was grazed by a bullet, police said. She was treated and released from a hospital. Police said the shooting does not appear to be random.
Investigators asked that anyone with information call Detective J. Feldman at 301-609-6474. Tips can also be submitted online at charlescountycrimesolvers.com. Anonymous tips can be left with Charles County Crime Solvers by calling 866-411-TIPS (8477). Crime Solvers is offering a cash reward for the arrest and indictment of a suspect, police said.