2 children among 5 killed when truck carrying ammonia overturns

Two children under the age of 12 were among five people killed when a semi-truck loaded with a toxic substance overturned in their rural Illinois community. The crash forced hundreds of nearby residents to evacuate their homes over the weekend, officials said.

The deadly highway wreck happened Friday night near the village of Teutopolis, authorities said. The semitruck was carrying several thousand gallons of anhydrous ammonia and caused a "large plume cloud" of the noxious gas to rise over the area, according to authorities.

Evacuated residents were allowed to return to their homes Saturday evening after the crash was cleared from U.S. Highway 40 and testing "indicated the danger from the anhydrous ammonia has dissipated," Teutopolis Assistant Fire Chief Joe Holomy said in a statement.

Effingham County Coroner Kim Rhodes confirmed two of the five deceased victims are under the age of 12.

The cause of the crash remains under investigation by the National Transportation Safety Board and the Illinois State Police.

"We offer our deepest sympathies to all those affected by the accident and chemical spill. First responders and emergency managers train for this and many other kinds of emergencies with the goal of minimizing impact to people and property," Clayton Kuetemeyer, deputy director of the Illinois Emergency Management Agency and Office of Homeland, said in a statement.

The incident unfolded around 8:40 p.m. local time when the semi-truck rolled over on the highway and spilled anhydrous ammonia on the roadway, causing "terribly dangerous air conditions in the northeast area," Effingham County Sheriff Paul Kuhns told reporters during a Saturday press briefing.

In addition to the five fatalities, "multiple injuries" were reported, according to the Illinois Environmental Protection Agency. Several vehicles were involved in the crash, state police said.

The semitruck was carrying 7,500 gallons of anhydrous ammonia, according to the Illinois Environmental Protection Agency. An estimated 4,000 gallons of the substance spilled from the tanker, officials said.

The accident scene was "large" and "complicated," Kuhns said.

About 500 people were evacuated when an evacuation zone of approximately 2 square miles was established on the east side of Teutopolis, authorities said.

The ruptured area of the tanker was patched, which "slowed it down" but did not immediately stop the leak, Teutopolis Fire Protection District Chief Tim McMahon said.

Anhydrous ammonia is a clear, colorless gas that is toxic. Effects of inhalation range from nausea to respiratory tract irritation, depending on the length of exposure, according to the Centers for Disease Control and Prevention.

The National Transportation Safety Board, in coordination with the Illinois State Police and the Effingham County Sheriff's Department, sent a 15-person team to conduct a safety investigation into the rollover crash, the agency said Saturday.

Representatives from the U.S. Environmental Protection Agency also responded to the scene.

Teutopolis is a small village in Effingham County, located about 92 miles southeast of Springfield, the capital of Illinois.