A San Francisco pizza shop fired an employee after a police union said several officers were told they were not welcome at the restaurant.

The San Francisco Police Officer's Association posted on Twitter Sunday that several officers went into Pizza Squared and were told they "were not welcome in the restaurant."

The union said it reached out to the owners about the "shameful and hateful actions of one of their employees."

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On Monday, the pizzeria tweeted that the employee was a trainee on his third day. 

"When our shift manager told us about the incident after it happened, we expressly told him we didn’t share his views & that he was out of line," the tweet states. "He was fired at the end of the day."

The restaurant said it apologized to the police union. 

Union President Tracy McCray told FOX San Francisco that police officers have dined at the pizza shop and never faced any mistreatment in the past. 

"We were pleased to receive an immediate response from the owners, including a sincere apology for their employee’s actions and a commitment to meet with the affected officers and make this unfortunate situation right," he said.

Over the years, some police officers across the country have been denied service at restaurants because of their chosen profession.