A Sheffield worker is understood to have died when the digger he was driving plunged into the water at docks near Grimsby.
A large-scale rescue operation, involving police divers and a search and rescue helicopter, was launched at Mineral Quay, Immingham Docks, around 8.30am on Monday.
Police confirmed the body of a man, who was understood to be the driver of the vehicle, was recovered from the water.
A Humberside Police spokesman said: “A man has died following an industrial incident at Immingham Docks.
“Police were called to the scene shortly after 8.30am to reports of a truck having entered the water at the dockside.
“Humberside Police are working with the Health And Safety Executive to establish the circumstances surrounding the incident.
“The man is yet to be formally identified.”
The incident happened close to a scrap metal site on Mineral Quay.
A worker on Immingham docks spoke of his shock.
“There were a lot of people saying a digger had gone into the dock and the driver was still in it,” he said.
“It’s definitely a shock. I’ve not seen anything like this before down here.”
The worker said: “All of the workforce is obviously in shock and it’s what everyone is talking about.”
He also said ships were prevented from entering the dock for around three hours while the rescue operation took place.
The Humber Coastguard from Hull and Cleethorpes were also called as well as members of Nottinghamshire Underwater Search & Rescue. East Midlands Ambulance Service was also on standby.