This drone footage of the devastation in Tianjin is eye-opening. With at least 50 dead, and many more injured, no cause for the blast has yet been identified.

A chemical odor hung in the air Thursday. Fires still burned in the thinly populated waterfront industrial district where the explosions went off. And the grim toll kept mounting.

Among the 50 confirmed dead are 17 firefighters, officials said Thursday. More than 700 people have been treated in hospitals, 71 in critical condition, the state-run Xinhua news outlet said. Dozens of people are reported to still be missing.

Authorities said more than 200 chemical specialists from the military had been sent in with detection devices. More than 1,000 firefighters have been trying to deal with the remaining fires.

The explosions originated at a warehouse site owned by Tianjin Dongjiang Port Rui Hai International Logistics Co., a company that stores and transports dangerous chemicals. Firefighters had reportedly been called to the area to tackle a blaze before the first blast went off.

Company executives have been taken into custody, state media said.

...

The first explosion was huge, and the second was even more powerful: the equivalent of 21 metric tons of TNT or a magnitude-2.9 earthquake, according to the China Earthquake Networks Center.