A vehicle emissions reduction device, which is mandated by the Environmental Protection Agency, forced an ambulance to shut down while carrying a suspect who was shot by Washington, D.C., police.

The EPA mandated device is meant to reduce diesel emissions and is required to be placed on all newer model diesel vehicles. The device can burn off diesel toxins automatically or manually, but if neither of those happen during the “re-generating cycle,” warning lights pop on and the vehicle is eventually forced to shut down.

“To my knowledge it’s never created a problem for us, but something different happened on this call,” DC Fire Deputy Chief John Donnelly told WUSA9, adding that it can be challenging to work within federal regulations.