A small Iranian passenger plane crashed while taking off from an airport near the capital, Tehran, state media reported.
The country's state-run media said at least 40 people were feared killed in the crash.
The aircraft, an Iran-140 jet typically used for short domestic flights, crashed near Mehrabad airport, west of Tehran, Iran's state-run IRNA news agency reported. The plane went down in a residential area after its engine went out, the agency reported.
"Initial reports indicate that the 48 people aboard the plane have been killed, including seven children," IRNA reported. It did not identify a source for its claim. State television said 42 people were aboard the plane when it crashed.
Iranian state television reported that the plane was an Iran-141 flown by Taban Air flight. IRNA said it was flown by Sepahan Air. The conflicting information could not be immediately reconciled.
The Iran-140 is a 52-seat passenger plane produced in Iran with Ukrainian technology.
Iran has suffered a series of airplane crashes, blamed on its aging aircraft and poor maintenance. Many of the Boeing aircraft in state-run Iran Air's fleet were bought before the country's 1979 Islamic Revolution, which disrupted ties with the US and Europe.
Iranian airlines, including those run by the state, are chronically strapped for cash, and maintenance has suffered, experts say. US sanctions prevent Iran from updating its American aircraft and make it difficult to get European spare parts or planes as well. The country has come to rely on Russian aircraft, many of them Soviet-era planes that are harder to get parts for since the Soviet Union's fall.
The last major airliner crash in Iran happened in January 2011, when an Iran Air Boeing 727 broke to pieces on impact while trying an emergency landing in a snowstorm in northwestern Iran, killing at least 77 people.
In July 2009, a Russian-made jetliner crashed in northwest Iran shortly after taking off from the capital, killing all 168 on board.
In February 2003 a Russian-made Ilyushin 76 carrying members of the Revolutionary Guard crashed in the mountains of southeastern Iran, killing 302 people aboard.