Engineers are investigating why a blade more than 20 metres (66ft) long fell off a wind turbine in Lincolnshire.
It is believed the blade came away from one of the 20 turbines at Conisholme Fen near Louth early on Sunday.
Ecotricity, which operates the site, said the turbines' manufacturers were on site and assessing the damage.
A spokesman said the turbines were in a very isolated location and there was no danger to property or the public. An inspection is due to be carried out.
The spokesperson added: "This has never happened before so we really have no idea what might have gone wrong.
"We will conduct a thorough inspection of the turbines to see if there is a problem and put it right."