Baltimore police were investigating a fight early yesterday between two off-duty city police officers that ended with one stabbed in the back. The fight occurred about 7:45 a.m. in the 3600 block of Raymonn Ave. in Northeast Baltimore. Police identified the officers involved as Walter Brown, 24, and Larry Worsley, 23, both assigned to the Central District. The officer who was stabbed, Brown, drove himself to Maryland Shock Trauma Center and was treated for minor injuries, said Officer Troy Harris, a police spokesman. Worsley also suffered minor injuries, Harris said. The cause of the fight remained under investigation. Police were trying to determine whether criminal and departmental charges should be filed, Harris said.