A security camera captured the moment a consignment of chlorine was dropped, releasing a dead gas cloud.
At least 13 people died and an estimated 250 people fell ill following the industrial accident at Jordan port.
The tank was dropped by a crane loading it onto a shop in Aqaba earlier today.
State TV broadcast the moment dockworkers were sent fleeing for their lives as the thick yellow cloud rolled towards them.
The Public Security Directorate, which initially described it as a gas leak, said authorities sealed off the area after evacuating the injured and sent specialists in.
State-run Jordan TV said 13 people were killed, while Al-Mamlaka TV, another official outlet, said 199 were still being treated in hospitals.
Dr. Jamal Obeidat, a local health official, urged people to stay inside and close windows and doors.
Aqaba is on the northern tip of the Red Sea, next to the Israeli city of Eilat, which is just across the border. Both are popular beach and diving destinations.
Eilat’s emergency services said in a statement that there was no impact on the city but that they were following the situation closely.
Operations at the port were paused while checks were carried out on nearby silos holding grain reserves.