unidentified gunman riding in a car near the U Street corridor in Northwest Washington opened fire Thursday afternoon, injuring two people, according to police and a D.C. council member.The shooting took place around 2:40 p.m. at 14th and V Streets NW. The intersection is one block north of the busy U Street corridor.Council Member Jim Graham (D-Ward 1), who said he was briefed by police, said authorities are investigating whether the shooting stemmed from a rivalry between two gangs, the “7th and O St. crew” and the “9th and R St. crew.”One victim was shot in the ankle, said Officer Tisha Gant, a police spokeswoman. A second victim also was injured, but the extent of that person’s injuries were not clear. Both were transported to a local hospital.Graham said authorities are looking for a...