Popular fast casual restaurant Chipotle Mexican Grill agreed to pay a $25 million criminal fine stemming from norovirus outbreaks that sickened customers from 2015 to 2018, prosecutors said Tuesday.

More than 1,100 patrons fell ill from the outbreaks that led to California -based Chipotle to be charged with two counts of violating federal food guidelines “by adulterating food while held for sale after shipment in interstate commerce,” the U.S. Attorney said in statement.

The $25 million penalty is “the largest fine ever imposed in a food-safety case,” prosecutors said.

“Chipotle failed to ensure that its employees both understood and complied with its food safety protocols, resulting in hundreds of customers across the country getting sick,” Los Angeles-based U.S. Attorney Nick Hanna said.

Chipotle confirmed the deal with prosecutors and said the company is “committed to continue enhancing its already robust food safety policies, practices, and procedures.”

“This settlement represents an acknowledgment of how seriously Chipotle takes food safety every day and is an opportunity to definitively turn the page on past events,” company chairman and CEO Brian Niccol said in a statement.

In the settlement, Chipotle admitted to a pattern of “store-level” missteps that included failed “exclusion of restaurant employees who were sick or recently had been sick, as well as a failure by restaurant employees to hold food at appropriate temperatures to prevent and control for the growth of foodborne pathogens,” according to a statement by prosecutors.

The settlement singled out Chipotle restaurants in Los Angeles and Boston, as well as other locations in California, Ohio and Virginia.

The Boston incident in December 2015 sickened several members of the Boston College Eagles basketball team.

And over the course of eight days in July 2018, about 647 people got sick after dining in Powell, Ohio, due to “critical violations of the local food regulations, including those specific to time and temperature controls for lettuce and beans,” prosecutor said.

The chain on Tuesday insisted it’s been improving safety standards since these outbreaks occurred.

“Over the last four years, we instituted several enhancements to our food preparation and food handling practices to lower the risk of foodborne illnesses,” company VP for food safety Kerry Bridges said in a statement.

“These measures include reducing the number of employees who come into contact with ingredients, safeguards to minimize the risk that an ingredient is undercooked, and sophisticated microbiological testing of raw ingredients to help ensure quality and safety before they are shipped to restaurants.”