Peloton Interactive on March 18 issued a safety warning to users of its high-end Tread+ treadmill after it learned about the death of a child involving the equipment.

CEO John Foley made the disclosure in a message to some customers. “I’m reaching out to you today because I recently learned about a tragic accident involving a child and the Tread+, resulting in, unthinkably, a death,” he wrote. “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.”

Peloton shares fell more than 3% in New York trading on March 18. In an interview with Bloomberg TV on March 17, Foley said “the future of fitness is in the home” and that the company’s addressable market is 200 million gym goers. This incident could put a question mark over this value proposition.

Foley said that Peloton builds all of its products with safety in mind, but told users of the Tread+ that they should keep children and pets away from the equipment at all times and store the Tread+ safety key away from children when it is not in use. “We are currently assessing ways to reinforce our warnings about these critical safety precautions to hopefully prevent future accidents,” he added.

U.S. hospital emergency rooms treated 68,296 injuries related to exercise equipment in 2019, according to the U.S. Consumer Product Safety Commission’s online database. The agency has reported two specific incidents related to Peloton equipment.

One report, involving a Tread+ filed in February, said a 3-year-old boy sustained “significant brain injury” after getting trapped under the equipment. After being discovered by his father, the child “was found to have tread marks on his back matching the slats of the treadmill, neck injury, and petechiae on his face, presumably from occlusion of blood flow,” the report said.

On March 17, the report was updated with a note from Peloton saying that the company had been told by a member that the child was “expected to fully recover.” It’s unclear if this is the same incident disclosed by Peloton on March 18. A Peloton spokeswoman didn’t respond to a request for comment.

In October 2020, a 42-year-old male reported a pedal on a Peloton Bike snapping off during use, but didn’t seek first aid. Peloton issued a voluntary recall on that part, according to the CPSC report.

Use of Peloton’s bikes and treadmills has skyrocketed over the past year as people tried to stay active at home while gyms closed due to the Covid-19 pandemic. In his email to Tread+ users, Foley said the need to take safety precautions “is especially true during what I hope is the final stretch of the pandemic where everyone is still at home.”

“There are no words to express the shock and sadness everyone at Peloton feels as a result of this terrible tragedy,” a Peloton spokeswoman added in a statement. “Out of respect for the family and their privacy, we won’t be sharing any additional information.”