East Sussex Fire and Rescue Service has been called to Euro Business Park in Newhaven this morning (Wednesday, January 30).
Crews are on the scene in New Road assisting Southern Gas Networks after a business had to be evacuated after a carbon monoxide alarm was triggered.
They were called to the incident at 9.59 this morning.
Firefighters wearing breathing apparatus are currently carrying out a search of the building to identify the source.
Paramedics are at the scene looking after anyone affected, said a spokesperson for East Sussex Fire and Rescue Service.
Sussex Police have have put a diversion for traffic in place.