A helicopter carrying Iranian President Ebrahim Raisi and his foreign minister crashed on Sunday as it was crossing mountain terrain in heavy fog, an Iranian official told Reuters, and rescuers were making their way to the site of the incident.The official said the lives of Raisi and Foreign Minister Hossein Amirabdollahian were "at risk following the helicopter crash", which happened on the way back from a visit to Iran's border with Azerbaijan."We are still hopeful but information coming from the crash site is very concerning," said the official, speaking on condition of anonymity.The bad weather was complicating rescue efforts, the state news agency IRNA reported. The chief of staff of Iran's army ordered all the resources of the army and the elite Revolutionary Guard to be put to use in the search and rescue operations.State TV stopped all its regular programming to show prayers being held for Raisi across the country and, in a corner of the screen, live coverage of rescue teams deployed on foot in the mountainous area in heavy fog.The rescue teams were expected to reach the site of the crash later on Sunday evening, state TV reported.Raisi, 63, was elected president in 2021, had been at the Azerbaijani border to inaugurate the Qiz-Qalaisi Dam, a joint project.Interior Minister Ahmed Vahidi told state TV only that one of the helicopters in a group of three had come down in the incident, and that authorities were awaiting further details.