Updated at 5:35 p.m. ET

Employees at Chicago's O'Hare International Airport's restaurants, bars and coffee shops went on strike at noon Thursday. HMSHost tells the Chicago Sun-Times that the restaurants are open and "operating smoothly."

"Don't get caught HANGRY!" warn the handbills the union has been passing out at airports across the country. "[M]ake sure you're not impacted, pack a snack!"

The workers are all employees of HMSHost International, the giant operator of airport and highway food services. They have been working under an expired contract since August, and two weeks ago, they voted to authorize a strike.

Unite Here Local 1, the union representing hospitality workers in the Chicago area and northwestern Indiana, said last week that it remained far apart from HMSHost on key issues under negotiation. The union says the negotiations affect more than 1,200 people who work as baristas, cooks, servers, bussers, and bartenders at O'Hare eateries including Starbucks, Tortas Frontera, Chili's and The Publican Tavern.

"It is unfortunate that Local 1 seems determined to inconvenience travelers despite our continued progress at the bargaining table," HMSHost said in a statement to the Chicago Tribune.

HMSHost told the Tribune that all the restaurants will remain open despite the strike. A union spokesman told the newspaper that pickets would be in place until at least 5 p.m. The next negotiations are scheduled for Jan. 11.

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