WHITEHALL, Pa. — Police are investigating an anonymous letter calling on a Pennsylvania day care center to fire a black worker because of her skin color.

The Bridge 2 Creative Leaning Center in Whitehall Township received an envelope Tuesday containing letters addressed to the owner and a worker, The (Allentown) Morning Call reported. The anonymous author purported to be a parent and suggested firing an unnamed worker because of her skin color.

Township police chief Michael Marks said he has never seen a letter so offensive in his 20 years of police work, and whoever sent it could face harassment and ethnic intimidation charges.

“It’s disturbing. This is not something you want to see in your community,” Marks said, adding that there have been no similar incidents reported in the township. “This is something we as a police department are going to take very seriously.”

Day care owner Dominique McKelley said she has several African-American staff members and students at the day care, which serves more than 130 children. She said security measures are already in place to protect children, but staff members are on added alert and are leaving the facility in pairs so no one is alone.

McKelley said she was nervous about revealing it to the worker believed to be the target, and choked up recounting the experience, the newspaper said.

“She started crying. She looked scared,” McKelley said. “She said she was going to quit. But I convinced her to stay. This has gotten everyone here so fired up.”

McKelley said she doesn’t believe a parent is responsible because the day care center established in 2009 is a close-knit community, but the center will seek prosecution of whoever is responsible.