Four people were wounded in a shooting outside a Portland high school on Friday, throwing an area in the north end of the city into chaos as medical responders rushed to the scene and the police searched for someone believed to be involved with a local gang. A 16-year-old girl was hospitalized in critical condition and two young men, ages 17 and 20, were in serious condition. A 19-year-old woman was treated for a graze wound. The victims were able to run into the school after the attack, a police spokesman said. Their names were not available. Rosemary Anderson High School, with about 200 students, is an alternative public school for students who have either been expelled from or dropped out of regular high school. The shootings occurred just after noon on an unseasonably warm and dry day when many students were outside, but a spokesman for the Portland Police Bureau, Sgt. Pete Simpson, said it was not clear whether the victims were specifically targeted or just happened to be in the wrong place at the wrong time.