(WHTM) – Fisher-Price is recalling about 21,000 Thomas & Friends train car toys due to a choking hazard.

A small plastic piece with a high-powered magnet inside can loosen or detach, possibly causing a child to choke or even swallow the magnet, according to the United States Consumer Product Safety Commission.

The recall involves about 21,000 of the Thomas & Friends Wooden Railway Troublesome Truck & Crates and Thomas & Friends Wooden Railway Troublesome Truck & Paint toys in the U.S. Around 400 more were sold in Canada.

The Truck & Crates toys (model number HBJ89) are black and gray with brown crates as cargo, while the Truck & Paint toys (model number HBJ90) are gray and black with gray paint cans as cargo.

The magnets are used to attach the affected toys to compatible Thomas & Friends train toys. The train cars have faces on them that look like the characters from “Thomas & Friends” children’s TV series.

There has been one report of a loose plastic connector detaching from the Thomas & Friends Wooden Railway, though no injuries have been reported so far.

Anyone with these toys is advised to immediately stop using them and go to the Mattel website for instructions on how to receive a pre-paid return label from Fisher-Price in order to get a refund.