North Wales Fire and Rescue Service say they are dealing with a fire on the Deeside Industrial Estate.
A spokesperson said crews were called to the incident in a building on 4th Avenue, Deeside Industrial Estate, at 12.58pm.
Eyewitnesses have described hearing loud bangs from the Ifor Williams Trailers factory. They say there were large clouds of thick black smoke, but that the fire is now largely under control.
Appliances from Deeside, Buckley, Mold, Holywell, Wrexham and St Asaph, as well as the Aerial Ladder Platform, the Environmental Protection Unit and the Incident Command Unit, were all sent to deal with the fire.
More top news
Exclusive figures given to ITV Cymru Wales show a steep rise in the number of people seeking advice for steroid use.
Cold, breezy and generally cloudy at first with further wintry outbreaks on the hills
All primary and secondary schools in Wales have been categorised in a new colour-coded system. Is your school green or red?