Four men have died in an industrial accident, police said last night. Emergency services were called to Claxton Engineering in North River Road, Great Yarmouth, just before 2.30pm yesterday.
One report said the four suffered fatal injuries when a steel structure fell or tilted onto them.
Norfolk Constabulary said officers were in the process of informing family members and no further details were available.
Det Chief Inspector Neil Luckett 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 today."
The company said: "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."
According to the company's website, Claxton "provides engineering and services to the offshore jack up drilling community across the life of the asset from pre-drilling to drilling, production and decommissioning".
The Great Yarmouth-based firm was founded in 1985 and has offices in Aberdeen and Dubai.
Earlier this month, Claxton reported it had developed a new
hydraulic riser, which saved a Norwegian client four and a half hours on its rig, equating to 1.8m.
The company also provided drilling risers for Encana Corporation's Deep Panuke field development off Nova Scotia, Canada.