A plant that makes bourbon, whiskey, gin and other distilled spirits accidentally concocted a chemical cocktail that spewed a dangerous fog over Atchison, Kan., on Friday.

The floating cloud that smelled strongly of bleach sent dozens of people to the hospital, spurred evacuations and closed major highways. A local emergency room treated at least 26 people for respiratory issues.

The chemical fog developed around 8 a.m. after workers at the MGP Ingredients' sewage facility inadvertently mixed two unknown chemicals.

"No fire, no explosion, just a plume developed when two chemicals were mixed with each other," City Manager Trey Cocking said at a press conference.

The plume of smoke from the spill floated over the city and prompted officials to urge residents to stay indoors. ‚ÄčArea schools evacuated thousands of students to a local Wal-Mart or the airport. City authorities said the gas cloud smelled strongly of bleach.

The Kansas Department of Transportation closed U.S. Highways 59 and 73 and Kansas Highway 7. The department reopened the roads about 11 a.m. as the cloud moved along the river channel and dissipated, spokeswoman Kim Qualls said.

The Kansas Highway Patrol used its helicopters to track the plume as it hovered over downtown Atchison and then floated west, Cocking said.

"Atchison residents: please shelter in place. If you are not in Atchison, please stay out of town," the Atchison County Emergency Management office wrote in a notice on its Facebook page.

City officials issued the all clear nearly three hours later after the cloud dissipated.