Iran: Investigation begins into crash that killed at least 77 during emergency landing (VIDEO)

Iran has begun investigating a passenger plane crash in the north-west of the country that killed at least 77 people.

The IranAir Boeing 727, carrying 105 passengers and crew, was traveling from Tehran to Orumiyeh, the capital of West Azerbaijan province and tried to land after announcing a technical failure to the control tower, the AP reports. It crashed in heavy snow and fog Sunday night, as reported by Al Jazeera.

The plane had already tried to land once when its second emergency landing attempt failed and the aircraft broke into pieces after crashing into farmland. Officials said that anywhere from 27 to 33 passengers were injured, while others walked away from the crash.

The accident is the latest in a series of air crashes in Iran in recent years.

The last major crash was in July 2009, when a plane caught fire mid-air and crashed into northern Iran, killing 168 people.

In 2003, an Iranian troop carrier crashed in the south-east, killing all 302 soldiers and crew on board.

Years of economic sanctions have left Iran with an aging civil fleet of planes that are poorly maintained.

According to the ISNA news agency, the aircraft that crashed was the oldest passenger aircraft still operating in the country, delivered to IranAir in 1974 as a used plane.

Still, Ahmad Majidi, the head of the road and transport ministry's crisis panel, told ISNA news agency that it appeared that bad weather was the cause of the crash.

"Based on the evidence, the plane's captain could not land at Orumiyeh airport due to bad weather conditions and he decided to return (to Tehran)," he said. "But for unknown reasons the plane crashed around five miles from the airport."

He said the plane's flight recorder had been located and would be sent to Tehran as part of the crash investigation.