John Velazquez, who was involved in a spill on Friday, was involved in another on Saturday at Belmont Park. Velazquez took off his first three mounts Saturday, then in his first mount back, fell aboard Imadeed as the horses hit the three-sixteenths pole in the Belmont Stakes Day fourth race, the WNBC.Pleasant County, with Eibar Coa up, fell over the downed horse and rider. She reportedly hit her head on the track, injuring her skull, and died instantly.On Friday, Renegade Warrior broke down in the Flash Stakes (gr. III) and Windsor Lodge fell over him. Both jockeys, Ramon Dominguez on Renegade Warrior and John Velazquez aboard Windsor Lodge, were conscious and walking after the horrific episode. Velazquez, however, went to North Shore University for observation after complaining of a sore right knee.On Saturday, both jockeys also got up. Coa was reported as uninjured. Velazquez took off the remainder of his mounts after complaining of soreness in his knee.Imadeed is a 5-year-old mare by Alydeed out of the Gate Dancer mare Imah. She raced for Claiborne Farm. She had taken the lead in the turn, but then relinquished it as they straightened for home. Imadeed bobbled just before going down in the Belmont stretch. She was removed from the track by ambulance with an ankle injury and was to have X-rays performed. She tore her suspensory and bowed a tendon, Dr. Larry Bramlage said. Further evaluation will occur Saturday night.Pleasant County, a 4-year-old mare by Pleasant Tap -- Star County, by Ogygian, was bred and raced by Edward Evans.The race was won by Too Scarlet.