Vital equipment used by firefighters was stolen as crews trained on the River Wear.
Firefighters had used two specialist trolleys or cradles to transport the engines for their inflatable rescue boat from the fire engine to the water’s edge at Claxheugh Rocks, by Sunderland Rowing Club.
They attached the engines to the boat and began their training on the water. When they returned at around 5pm on Wednesday, both cradles were gone.
Without them, the fire crews are unable to safely transport or store the boat's engines.
The rescue service says this could seriously affect their ability to carry out water rescues and support at water-based emergencies.
In an effort to get the trolley returned, the fire service shared a photo of the equipment.
A spokesperson for the Tyne and Wear Fire and Rescue Service (TWFRS) said: "If you were involved in the incident and you or someone you know currently has the cradles, please return them to any Tyne and Wear fire station.
"The important thing is that we get this lifesaving equipment back as soon as possible, to minimise the risk to public safety."
Chris Lowther, chief fire officer and chief executive for TWFRS, shared the appeal online and wrote: "Howay man. Can someone decent get these back to us? We need this stuff to save lives like."
Northumbria Police have been informed of the theft and are investigating.
A spokesperson for police said: "At about 5pm yesterday police received a report that two boat trolleys belonging to Tyne and Wear Fire and Rescue Service had been stolen from the area of Riverside Park in Sunderland.
"Inquiries into the incident are ongoing and anyone with information about the location of the trollies is encouraged to contact police on 101 quoting log 755 07/08/19."
