Thousands evacuated after US fertilizer plant fire sparked fears of explosion

About 6,500 people were under evacuation orders for three days after a fire broke out at a North Carolina fertilizer plant, which officials said risked becoming one of the biggest explosions ever to occur in the US.

The fire continues to burn. The plant contains roughly 600 tons of ammonium nitrate, a highly volatile chemical compound that is used to make both fertilizers and explosives.

The Winston-Salem fire erupted in the northern part of the city of 250,000 on Monday, though the cause remains unknown. Roughly 2,500 homes, several schools and churches, a correctional facility and other commercial and government buildings were within a one-mile evacuation radius of the facility, though late Thursday was reduced to 1/8 mile, a radius inside which there are no homes, local news reported. Wake Forest University, which sits just outside the evacuation zone, cancelled classes, urging students in dorms to stay indoors and close their windows.

Fertilizer explosions are among the deadliest industrial accidents in the US. In 1947, nearly 600 residents died from an ammonium nitrate blast in Texas City, Texas. In 2013, 15 people were killed by the ammonium nitrate explosion at another facility in West, Texas.

This story was updated with additional news on Friday 4 February