Five people were killed when a rescue helicopter crashed into a utility pole in Iran’s western province of Chaharmahal and Bakhtiari, reported state television.
The aircraft was trying to airlift a pregnant woman, but did not make it to her location on Monday, it said.
Pirhossein Koulivand, head of the country's emergency medical services, told the TV three of the five aboard were flight crew and two were rescue workers.
Iranian aircraft crashes have been blamed on its old fleet and years of international sanctions over the country's nuclear program.
In 2016, a helicopter belonged to the oil company crashed in the Caspian Sea, killing five onboard. In 2015, four died in a crash of a helicopter transferring an injured oil staffer to hospital from an offshore oil platform.
Last year, 66 passengers on board an Iranian domestic flight were killed when their aircraft crashed into the Zagros Mountains.
In January, an Iranian Boeing 707 cargo plane coming from Kyrgyzstan crashed while trying to land west of Iran's capital. Only one person of the 16 on board survived.
