Inspectors from the Health and Safety Executive (HSE) are at the scene of an incident at the Royal estate at Sandringham.
A spokesman for the HSE said:
No formal investigation has been launched, but we do have inspectors at the scene with police who are making initial enquiries.
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Icy stretches will form tonight as temperatures drop and wintry showers develop later.
A woman has been banned from keeping all animals for three years after admitting neglecting her cat and four kittens - two of whom died.
With the cold weather expected to last for at least the next five days, the Met Office has issued various snow and ice warnings.