At least 19 cadets at a military-style youth academy in the Washington, D.C., area were transported to hospitals Sunday after experiencing symptoms of an unknown illness. The incident prompted a mass casualty response.

Emergency crews were dispatched to the Capital Guardian Youth Challenge Academy in Laurel, Maryland, after cadets began falling ill following their midday meal, according to the DC National Guard. The academy, operated by the DC National Guard, is a program designed for at-risk teenagers.

One parent reported that blood tests conducted on their son at a hospital indicated elevated carbon monoxide levels. The son reportedly developed delayed symptoms, including dizziness, headaches, and nausea, hours after other cadets were taken for treatment. The parent also stated that the academy decided to temporarily close following the event.

However, officials from the Anne Arundel County Fire Department conducted a carbon monoxide investigation and reported no elevated levels of the gas, according to local reports.

While the cause of the illness has not been officially confirmed, officials stated it could be related to food. The DC National Guard emphasized that the health and safety of cadets and staff are their highest priorities and that they are collaborating with emergency medical personnel and public health authorities as the investigation proceeds. Of the 19 cadets sent to area hospitals, one adult was evaluated at the scene and declined further medical treatment.