A commission was established later in the day to investigate the accident. It was headed by Valery Legasov, First Deputy Director of the Kurchatov Institute of Atomic Energy, and included leading nuclear specialist Evgeny Velikhov, hydro-meteorologist Yuri Izrael, radiologist Leonid Ilyin, and others. They flew to Boryspil International Airport and arrived at the power plant in the evening of 26 April. By that time two people had already died and 52 were hospitalized. The delegation soon had ample evidence that the reactor was destroyed and extremely high levels of radiation had caused a number of cases of radiation exposure. In the early daylight hours of 27 April, approximately 36 hours after the initial blast, they ordered the evacuation of Pripyat. Initially it was decided to evacuate the population for three days; later this was made permanent.