New York City police determined there was nothing criminal afoot when three officers got Shake Shack milkshakes that might have been accidentally tainted with a cleanser.

Police came to the determination after “a thorough investigation," NYPD Chief of Detectives Rodney Harrison said in a tweet early Tuesday.

The officers complained of feeling ill upon sipping the shakes and ended up going to a hospital. Harrison said they were fine.

Several of the city's police unions pounced on the incident as an example of an anti-police attack, initially claiming the officers were intentionally poisoned.

The Police Benevolent Association, which represents patrol officers, said in an alert to members that the officers discovered “a toxic substance, believed to be bleach," was added to their beverages.

The Detectives' Endowment Association said in a statement that “three of our brothers in blue were intentionally poisoned by one or more workers.”

Shake Shack tweeted that it was “horrified” by reports of the alleged contamination. The New York City-based fast food chain said it was working with police in the investigation.

But by morning, the police unions had taken down their statements after the department's investigation concluded that whatever had happened to the drinks was an accident.

In an appearance on the local cable news station NY1, Harrison attributed the incident to “maybe a little bit of a misunderstanding regarding how they clean the items that made the beverage.”

Asked about the initial police union claims that the officers had been purposely poisoned, Mayor Bill de Blasio accused them of “sowing division.”

“I’m just sick of it. I’ve been sick of it for years," the Democrat said. "They try to undermine progress.”

Police union officials have complained in recent days that an anti-police atmosphere is endangering officers in the city and elsewhere.

In New York City, officers have been stabbed, clubbed with bricks, hit with cars and shot at in recent days, though many of those incidents have taken place away from street demonstrations over the death of George Floyd in Minneapolis on May 25.

News from © The Associated Press, 2020