RIVERSIDE, Calif. (AP) — Starbucks apologized to two sheriff’s deputies in California and said it would carry out an internal investigation after complaints by the sheriff that the coffee retailer’s employees refused to serve the officers, the Los Angeles Times reported.

The alleged mistreatment of the Riverside County sheriff’s deputies took place Thursday at a Starbucks near the campus of the University of California, Riverside.

The officers, who were in uniform, stood at the counter for about five minutes without being served and eventually decided to leave, according to statements from Starbucks and social media posts by Sheriff Chad Bianco.

“There is simply no excuse for how two Riverside deputies were ignored for nearly 5 minutes at our store on Thursday evening,” a Starbucks spokesman said in a statement. “We take full responsibility for any intentional or unintentional disrespect shown to law enforcement on whom we depend every day to keep our stores and communities safe.”

The Riverside incident marks the third time this year that Starbucks has been accused of disrespecting law enforcement officers. In July, six officers in Tempe, Arizona, said a barista asked them to move away from a customer who had complained that their presence was making him nervous. Starbucks apologized to the officers.

In November, a police chief in Oklahoma complained after a Starbucks employee labeled cups for several officers with the word “PIG.” Starbucks again apologized and fired the employee.

Bianco referred to the prior incidents Friday, writing on Twitter, “The anti police culture repeatedly displayed by Starbucks employees must end.”