Peloton is warning owners of their treadmills to keep children away, after an accident involving the company’s Tread+ product in which a child died.

Peloton’s CEO, John Foley, sent a letter Thursday to owners about the warning.

“I recently learned about a tragic accident involving a child and the Tread+, resulting in, unthinkably, a death,” the statement posted to the company’s website reads.

“While we are aware of only a small handful of incidents involving the Tread+ where children have been hurt, each one is devastating to all of us at Peloton, and our hearts go out to the families involved.”

No other details about the incident were shared by Foley, the company said they will not release more information “out of respect for the family and privacy.”

The letter urges owners to keep children and pets away from Peloton exercise equipment, and to remove the safety key after working out to stop others from starting the equipment accidentally.

The U.S. National Institutes of Health reported in a 2014 study that about 25,000 kids under 10 are injured by exercise equipment every year, according to CNN.