TEHRAN, Iran –  Iran’s official news agency says a rescue helicopter has crashed in the Persian Gulf, killing at least two people on board.

IRNA reported that the helicopter was flying from an offshore rig toward Kish Island on Tuesday, transporting an oil worker who had suffered a heart attack. It says the oil worker and a paramedic died in the crash. Another two passengers are missing, and the pilot survived.

Aviation crashes in Iran are often blamed on the country’s aging aircraft fleets, which were poorly maintained during years of sanctions over Iran’s nuclear program.