At least five people were killed while five others were left injured after a truck carrying thousands of gallons of poisonous liquid collided causing a chemical spill in Illinois and prompted an evacuation on Friday night, the Effingham County Coroner's Office said.
Around 9:25pm, on Friday, the truck crashed in Effingham County, a half-mile east of Teutopolis, locatedabout 92 miles (148 kilometres) southeast of Springfield, ABC News reported.
Illinois State Police revealed that a toxic liquid, anhydrous ammonia was spilled on Route 40 after a lorry transporting it toppled.
Two children under the age of 12 were among those killed in the collision, according to the coroner's office. Three of the victims are from Teutopolis, while the other two are from Missouri and Ohio.
The coroner's office reported that five further people were flown to hospitals for treatment.
While crews tried to stop the leak and first responders and other emergency personnel continued to attend to the incident, traffic was shut down, according to the police.
The crash caused a "large plume cloud of anhydrous ammonia on the roadway that caused terribly dangerous air conditions in the northeast area," said Effingham County Sheriff Paul Kuhns.
Following the incident, about 500 people were evacuated, with the evacuation area covering a region of about 2 square miles on the east side of Teutopolis, according to police.
The Illinois Emergency Management Agency and Office of Homeland Security have announced that the homeowners are now permitted to return to their houses after the evacuation order was removed on Saturday evening.
"Testing has indicated that the danger from the anhydrous ammonia has dissipated. We have notified residents that they may return home," said Teutopolis Assistant Fire Chief Joe Holomy.
According to the Illinois Environmental Protection Agency, the semi-truck was carrying approximately 7,500 gallons of anhydrous ammonia at the time of the accident and an estimated 4,000 gallons were spilt.
The accident scene was "large" and "complicated," Kuhns said.
Anhydrous ammonia is toxic and can be a health hazard if safe handling procedures are not followed. Effects of inhalation of anhydrous ammonia range from lung irritation to severe respiratory injuries, with possible death at higher concentrations. The chemical is also corrosive and can burn the skin and eyes.
"It's bad stuff if you breathe it especially because it gets in your airways, in your lungs and it burns," said Kuhns.
The tanker that contained anhydrous ammonia has been drained, patched and taken to a secure location pending an investigation by the National Transportation Safety Board, IEMA said.
Meanwhile, authorities are investigating the cause of the crash.