Police are investigating another stabbing at Hempstead High School.Officials say the victim is a night student who was stabbed in the arm. A family member told News 12 Long Island that the assailant is not a student at the school.The stabbing is the second within the last two months at the school. In January, 15-year-old Michael Alguera was fatally stabbed on the school's handball court.One group is offering to help the school with security, arguing the school desperately needs it. The president of N.O.B.L.E. says the school increased its security for dismissals, but that security needs to be heightened for all activities and events in order to be effective.