The California Labor Commissioner’s Office fined 18 Los Angeles garment manufacturers and contractors more than $682,000 this month for labor law violations, the office announced Friday.

The violations included failing to have workers’ compensation insurance, which garnered the largest fine of over $404,000, and failing to give employees itemized statements showing the number of hours they worked.

“Sweatshop operators threaten garment workers’ rights and undermine honest employers in the industry, making it difficult for legitimate garment businesses to stay in operation,” Labor Commissioner Julie Su said in a news release. “These illegal entities should take note: We will shine a light on the underground economy.”

Enforcement officers from the Labor Commissioner’s Office inspected 22 worksites, seizing 85 bags of garments worth almost $156,000 during the two-day operation, which began Sept. 7, officials said. The 18 sites that were fined employ almost 300 workers.

The Labor Commissioner’s Office said it was also pursuing wage theft investigations for some of the employers.