(This story was updated at 6:50 p.m. ET Thursday.)

Sweet Leaf, one of Colorado’s largest marijuana retail chain operators, had all of its Denver-area stores shuttered Thursday as part of police raids that resulted in 12 arrests.

Twenty-six of the vertically integrated company’s licenses have been suspended, according to Dan Rowland, spokesman for the Denver Department of Excise and Licensing.

The Denver Police Department and other agencies executed search and arrest warrants on eight marijuana retail stores across the metro area.

The operation is the result of an extensive, year-long criminal investigation into illegal distribution of marijuana at those locations, according to a news release.

The Colorado statute allows for the personal use of marijuana, specifically the possession, use, display, purchase and transport of 1 ounce or less of marijuana.

Officers arrested 12 suspects who are currently being held for Investigation of Illegal Distribution of Marijuana.

The suspects’ names, booking photos and arrest documents weren’t immediately available because the operation and booking process are still underway.

Sweet Leaf said it was “surprised” by the raids.

In a statement to Westword, a Denver alternative weekly, the company said:

“It is unclear at this point exactly what actions, if any, Sweet Leaf took to cause the city to issue this order. Sweet Leaf is cooperating with the authorities to resolve this issue and hopes to have all of their stores back in operation as soon as possible.”

Sweet Leaf’s website lists 10 recreational and medical marijuana retail stores in Denver. Sweet Leaf also has a retail outlet in Portland, Oregon.

In addition, the Denver-based company operates cultivation facilities.

Rowland said Ashley Kilroy, the licensing director for the department, signed the order of summary suspension.

The official order states that Kilroy reviewed an investigation by Denver police and found:

“Reasonable grounds and probable cause exists to believe that Respondents have engaged in deliberate and willful violations of state and local laws or regulations, and/or that the public health, safety, and welfare requires emergency action.”

The company, which boasted over 350 employees in April, had revenue of $60 million in 2016.

Bart Schaneman can be reached at [email protected]