RIO DE JANEIRO — A small executive jet crashed at Rio's domestic airport Thursday, but all three aboard were rescued without serious injuries. A spokesman with the Brazilian government's airport authority said the aircraft landed normally in clear weather, "but for reasons that are not yet known, it was unable to stop and skidded off the runway into the sea." The official spoke on condition of anonymity as he was not authorized to discuss the matter. The Learjet was operated by the OceanAir air taxi service and was carrying only three crew members, according to a statement from the company. It said they suffered no serious injuries. Government authorities and OceanAir are investigating the accident. Television images showed the intact jet floating in the waters of the Guanabara Bay, just a few feet from the runway. Firefighters entered the water to secure the aircraft with ropes. The Santos Dumont airport closed because of the accident, but was reopened in the afternoon.