A fire at a fertiliser plant broke out at around 7:30pm local time on Wednesday evening in the small farming town of West in central Texas.
The local voluntary fire service responded to the fire, but less than an hour later there was a very large explosion at the plant.
An amateur photographer captured the blast from his car two fields away.
The sound of the blast and the mushroom-shaped cloud it created were both perceptible miles away from the plant.
Emergency calls made after the explosion and later reports suggest that a few firefighters were still in the plant when the explosion occurred.
The force of the blast decimated an apartment block and nursing home in the immediate vicinity, and damaged houses within a five-block radius.
Most residents of the town were evacuated as quickly as possible.
Emergency workers are fearful about the release of a chemical fertiliser called Anhydrous Ammonia, which can cause severe burns and breathing difficulties and is potentially fatal.
Local residents worked with the emergency services to rescue residents from the nearby West Rest Haven nursing home and to perform door-to-door checks.
At least 160 casualties were taken to hospitals in Waco some 20 miles away.
A sports field at a nearby secondary school was appropriated as a makeshift first aid centre while residents gathered at the town's community centre in search of information.
In the town of Abbott, five miles up the road, a school hall was prepared to receive residents of West who lost their homes in the blast.