It is feared four workers have died after an industrial accident in Great Yarmouth, Norfolk.
The emergency services were called to nearby Claxton Engineering in the North River area, following reports of an accident at 1420 GMT.
The Ambulance, fire and Police services were all called to the scene, and the Health and Safety Executive have been informed of the incident.
The Norfolk Constabulary have confirmed that there have been fatalities, but would not reveal the number of lives that had been lost.
Speculation has suggested that four people have suffered fatal injuries after a large steel structure fell on top of them.
Claxton is an offshore engineering company.
The men were between the ages of 26 and 42 and all from the Bury St Edmunds area. Specialist officers are with their families.
An investigation has begun with Norfolk and Suffolk Police and the Health and Safety Executive are working in partnership at the site to try and establish the cause of the tragedy.
Claxton Engineering Services Limited have released a statement, saying building works was being undertaken at the site by an external contractor.
The statement added: “Everybody at Claxton is deeply saddened by what has occurred… and the company’s thoughts and sympathy are with the families of the four men.”
Police, ambulance and nine fire crews attending the scene of the accident at 1420 GMT including a search and rescue unit. The men died at the scene.
Det Ch Insp Neil Luckett said: “This is a complex investigation and our enquiries – including assessments at the site – are likely to continue for several weeks.
“We will not be drawn into conjecture on the nature of the incident.
“The aim of our investigation is to establish the full circumstances around what happened on the site yesterday.
“This is a distressing time for the families of those who sadly lost their lives and our thoughts go out to them.”
A post-mortem examination will be taking place on Monday in order to try and determine the cause of death.