A 27-year-old Reading man was shot and killed on the street in Lawrence on Sunday afternoon, according to the Essex district attorney’s office. Martin Butts was shot near 115 Union St. at about 12:30 p.m. and was taken to Lawrence General Hospital, where he was pronounced dead, said Carrie Kimball-Monahan, a spokeswoman for the district attorney’s office. Massachusetts State Police are investigating the killing.