A driver was injured when the trailer he was driving flipped onto its side on Tarxien Road, Gudja, on Thursday afternoon.
The police said the accident happened at 11.45am when the 51-year-old from Mqabba lost control of his vehicle.
The driver was given first aid and hospitalised in serious condition. Personnel from the Civil Protection Department worked to make the road safe after fluids leaked from the trailer.
The police are investigating.