MADRID - AUTHORITIES are investigating what caused a Spanish airliner to crash on takeoff from Madrid in a fiery accident that left 153 people dead.

Spain is in mourning over its worst airline disaster in nearly 25 years.

Flags are flying at half-staff in Madrid, and three days of mourning have been declared.

The king and queen plan on Thursday to visit a makeshift morgue where relatives are waiting to claim the remains of their loved ones.

Only 19 people survived on Wednesday's crash of a Spanair plane bound for the Canary Islands.

Spanair says it does not know the cause. Spanish media say one of the engines may have failed or exploded during takeoff. -- AP