A health and safety investigation is under way after four men died in an industrial accident.
The men, who have not yet been named, had been working at the site of offshore engineering company Claxton Engineering in Great Yarmouth, Norfolk.
The firm said building work was being carried out by external contractors at their premises where the accident happened just before 2.30pm on Friday.
Reports suggested a steel structure may have collapsed on the men.
A statement released by Claxton said: “Claxton Engineering Services Limited can confirm that an accident occurred at its premises in North River Road, Great Yarmouth where construction work on a new facility is being carried out by external contractors.
“We are also able to confirm that four men have tragically lost their lives in this incident which is now being investigated by the Norfolk Constabulary and the Health and Safety Executive. The company is fully co-operating with the investigation.
“Everybody at Claxton is deeply saddened by what has occurred today and the company’s thoughts and sympathy are with the families of the four men.”
Police, ambulances and nine fire crews including urban search and rescue units attended but the men died at the scene.
A joint investigation has been launched by Norfolk and Suffolk Major Investigation Team and the Health and Safety Executive (HSE).
Det Chief Insp Neil Luckett from the major investigation team said: “This is a tragic event and we will be working closely with the HSE to establish the full circumstances surrounding the incident. This may be a lengthy process. Our thoughts are with the families of the men who died.”