One construction worker was killed and two others seriously injured when a huge wall collapsed on Al-Haj Street here, Saturday. The three were working at the site of a warehouse to erect a supporting wall for the structure when it collapsed on top of them without warning. Rescue teams were rushed to the scene but by the time they managed to extract the three from beneath the piles of rubble, one was already dead. A Civil Defense spokesman said that an independent investigation had been set up to look into the incident.