By Scott Malone and Ian Simpson BALTIMORE (Reuters) - The mayor of Baltimore on Sunday lifted a night curfew imposed on the city last week to stem a spate of looting and arson that followed the funeral of a young black man who died from injuries suffered while in police custody. Mayor Stephanie Rawlings-Blake said she believed sufficient calm had returned to allow her to end the 10 p.m.-5 a.m. curfew, which took effect last Tuesday after protests over the death of 25-year-old Freddie Gray turned violent on Monday. "I believe we have reached that point today." The mayor said the Maryland National Guard would begin withdrawing from the streets over the next week. The surprise announcement on Friday by the city's chief prosecutor that she was bringing criminal charges against the six police officers involved in Gray's arrest has helped to defuse outrage over his death.