People observe five minutes of silence for the victims of the Spanair jet crash in front of Madrid city government building, 21 Aug 2008

Spain has begun three days of national mourning following the country's worst air disaster in more than two decades.

There were 153 people killed Wednesday at Madrid airport when the plane, operated by Spanair, veered off the runway on takeoff, broke into pieces and burst into flames. Most of the 19 survivors were injured.

Investigators have not theorized publicly on the cause of the accident. Authorities say the plane had been delayed earlier Wednesday by a problem with an air intake gauge that was resolved before take-off.

Spanish media quote witnesses as saying the doomed plane's left engine caught fire moments before the crash.

Officials say flight data recorders have been recovered and may help determine the cause of the crash. Investigators have already ruled out foul play.

The MD-82 aircraft was bound for the Canary Islands, a popular tourist destination.

Some information for this report was provided by AP and Reuters.