(CNN) Eric Trump , son of President Donald Trump, said Tuesday he was spat on by an employee at a Chicago-area restaurant.

"It was purely a disgusting act by somebody who clearly has emotional problems," the President's third child told conservative site Breitbart News by phone Tuesday evening.

The Chicago Police Department was on the scene and assisted Secret Service, per CPD spokesman Anthony Guglielmi.

"CPD was on scene and assisting the United States Secret Service with a law enforcement matter. Any and all inquiries regarding a federal protectee must be directed to the Secret Service," Guglielmi tweeted

A United States Secret Service spokesperson declined to comment to CNN, and did not respond to inquiries on whether charges had been filed.

Eric Trump cast blame for the incident, which took place at upscale cocktail bar and restaurant Aviary, more broadly on the Democratic Party.

"For a party that preaches tolerance, this once again demonstrates they have very little civility. When somebody is sick enough to resort to spitting on someone, it just emphasizes a sickness and desperation and the fact that we're winning," he told Breitbart.

Trump, who, along with his brother, leads their father's real estate business, was in town for a visit to Trump Hotel Chicago

"We did not witness the incident and we are just beginning to learn the details. What is certain is this: no customer should ever be spit upon," The Aviary said in a statement Wednesday.

The employee involved in the incident has not yet been spoken to, but has been placed on leave by its human resources team, The Aviary said.

The business also said it is being subjected to online harassment in the wake of the incident.

"Hundreds of people are calling for the demise of our business, threatening our employees, and posting fake reviews... they are wrong to do so based on the actions of a lone individual," the restaurant said in the statement. "So too, however, are those people wrong who are praising this as an act of civil disobedience."