At least 35 miners were killed by an explosion at a coal mine in northern Iran, according to state media and semi-official news agencies.
Media reports say the explosion at the Zemestanyurt mine might have occurred during a shift change when workers attempted to jump start a locomotive.
Iranian media said more than 30 of the injured were transferred to nearby hospitals.
The semi-official Fars news agency reported earlier that more than 50 workers were trapped in a two-km-long tunnel filled with gas that hampered rescue efforts.
President Hassan Rouhani has sent Minister of Labour and Welfare to the mine in order to oversee the rescue operations and treatment of victims, state news agency IRNA reported.
Iran extracted 1.68 million tons of coal in 2016, an increase on previous years, thanks to an easing of international sanctions. It uses most in domestic steel production and exports only a fraction.