Around 1730hrs units were dispatched to the 10300BLK of White horse circle in Lake Linganore for a child that had fallen out of a second floor window, while enroute to the run the engine was added by car-15 due to mechanism of inj, units arrived to find a 5yom that was conscious and alert, the child had fallen aprox 20 ft onto the ground and had a left arm inj, after a consult with JOHN HOPKINS PEDS the Helocopter was requested for the CAT-C PRI-2 CHILD, RE-153 had the lz at Linganore pool and the child was flown to HOPKINS.