A police officer shot a New Hampshire man in the buttocks on Saturday after he allegedly crashed his car into a police cruiser and fled, according to the Essex County district attorney’s office. Alexander Castro, 20, of Salem, N.H., was hospitalized with injuries that were not life-threatening. Police officers responding to reports of a loud party on Bennington Street around 5 a.m. Saturday observed Castro driving erratically in a 1995 Honda Civic, Essex district attorney spokeswoman Carrie Kimball-Monahan said in a statement, adding that Castro drove into one of the police and Lawrence Police Officer John Tully fired one shot at Castro’s car. Police tracked Castro to Salem using his license plate number, the statement said. Castro will face charges in Lawrence District Court of assault and battery with a dangerous weapon, operating to endanger, and failure to stop for a police officer. Tully was placed on paid administrative leave, the statement said.