April 25 (UPI) -- An ammonia leak in a Chicago suburb left dozens of people hospitalized Thursday, including seven listed in critical condition, the local sheriff's office said.
The incident happened in the pre-dawn hours in Beach Park, Ill., when two tanks containing anhydrous ammonia began leaking. A tractor was pulling the containers down the road when the toxic fumes prompted emergency calls about a possible vehicle fire.
The Lake County Sheriff's Office said two officials with the department responded to the call and were overwhelmed by the cloud of fumes. Some 140 first-responders responded to the incident.
Among the 37 hospitalized were 11 firefighters, two deputies and one police officer. One firefighter was listed in critical condition.
Officials ordered residents within a 1-mile radius of the leak to shelter in place, close all windows and turn off ventilation systems. The order has since been lifted.
"I wish to take a brief moment and commend all of our Lake County Sheriff's deputies, police officers from nearly 20 area police departments and all of the firefighters who risked their lives today to help others," Sheriff John Idleburg said.
He said law enforcement officials were investigating the cause of the chemical leak.