At least five people were killed and six taken to hospital following an explosion in a fireworks factory on the outskirts of this Spanish capital on Monday.Emergency services, including 10 fire engines, were soon on the scene of the accident, but their attempts to reach the exact area of the explosion were hampered by thick smoke and several smaller explosions which followed the main blast, Xinhua reported.In the confusion which followed the explosion, four people were reported as missing, but the Government Delegate for Zaragoza, Gustavo Alcalde later confirmed the five deaths.Two of those taken to hospital were in a condition which is described as "very serious", suffering from blast injuries and burns, while the condition of the other four is described as "serious".