A policeman prevents onlookers from getting close to the scene where a Tupolev Tu-154 passenger plane crashed near the city of Qazvin, about 150 km (93 miles) north of Tehran, July 15, 2009. The Caspian Airlines aircraft crashed in northwestern Iran on Wednesday on its way to neighboring Armenia and all 168 people on board were killed, Iranian media reported. REUTERS/ISNA Stringer

Iranian rescue teams are searching for the black boxes where an Iranian airliner en route to neighboring Armenia crashed shortly after takeoff killing all 168 passengers on board.

Russian-made Iranian passenger plane with 153 passengers and 15 crew on board crashed into a field north-west of the capital and shattering it into flaming pieces.

The plane's tail had caught on fire and circled the air several times before it crashed according to an eyewitness who told the Associated Press.

The cause of the accident of the aircraft operated by Iran Air Tours remains unknown but it is believed to have resulted from a technical failure, the two black are essential to help determine what happened to the crashed jet.

The Civil Aviation Organization of Iran said over 100 rescue workers were at the scene to help with the search and rescue operations.