Ukraine’s embassy in Iran has deleted a statement posted on its website that blamed the deadly plane crash near Tehran on engine failure, and Ukrainian President Volodymyr Zelensky has vowed to open up criminal proceedings into the disaster that left 176 people dead. Ukraine’s embassy initially agreed with Iranian statements that the Wednesday morning crash was due to a mechanical failure—but the embassy later issued a new statement omitting the mention of engine failure as the cause. It also said any previous comments about the cause of the crash weren’t official and should be discounted. Zelensky said Ukraine’s entire civil aviation fleet will be checked for airworthiness and criminal proceedings will be opened. Ukraine International Airlines said the plane in question had its last scheduled maintenance on Monday, and showed no sign of any problems prior to takeoff. The Boeing 737 went down after taking off from Imam Khomeini airport in Tehran, killing all 176 people on board.