A scrap yard fire in Tainan's Annan District turned into a chain of explosions because the pile held aluminum and magnesium — bad news for the 15 people hurt and the dozens of homes damaged nearby.

• Firefighters could not spray water directly on the blaze, because hot aluminum and magnesium react violently with water and make the fire worse.
• Crews had to hold a line from a distance and cool the edges while waiting for sand and foam to smother the flames.
• Investigators found waste oil drums stacked alongside the metals, which pushed the blast force much higher.
• Reactive metals like these are supposed to be sorted and stored apart from water and heat sources, and the city says it never got any application to store waste at the site.
• Air monitoring around the fire came back normal apart from a brief ammonia reading during the heaviest smoke, which triggered downwind alerts for Annan and Yongkang.

Outlook: The site has been covered with soil to stop it reigniting, and attention now turns to who dumped industrial waste there without permission.