A 17-year-old boy was shot and critically wounded Tuesday in Englewood.The boy was sitting in a car in a vacant lot just before 3 p.m. in the 7400 block of South Lowe Avenue when four people walked up to him and opened fire, Chicago police said.He was shot in the chest and was taken in critical condition to University of Chicago Medical Center, police said.No one is in custody, and Area One detectives are investigating.