A bronze statue worth £3m ($5.3m) by sculptor Henry Moore has been stolen from the grounds of a museum.
Thieves used a flatbed lorry to remove the sculpture
Two vehicles gained access to the courtyard of the Henry Moore Foundation in Perry Green, Much Hadham in Hertfordshire, on Thursday evening.
Three men then loaded the huge statue of "a reclining figure" onto the back of a Mercedes lorry using a crane.
Officers investigating the theft believe it could have been stolen for scrap value.
The 1969/1970 work is 3.6m long, 2m high by 2m wide and weighs 2.1 tonnes.
One offender is described as wearing a hooded jacket and one a baseball cap.
The Mercedes is a flatbed lorry, possibly red with a crane on the back.
A second vehicle used by the men is thought to have been an old-style Mini Cooper, police said.
Det Sgt Graeme Smith said: "This is a very valuable statue and we are working closely with the Henry Moore Foundation to ensure its safe return."
Mr Smith said officers were keeping an open mind as to the motive behind the theft - which was captured on CCTV - but added: "We are fearful it is possibly going to be sold for scrap, which would be a travesty."
A substantial reward has been offered by the Foundation for information leading to its recovery.
A spokesman for the Henry Moore Foundation said there would now be a reassessment of security in the wake of the theft.
Gareth Spence, from the Foundation, told BBC news that the statue was in the farmyard area of the museum and was in the process of being moved to another location.
"It is quite a daring thing to do, and it will cause a reassessment of our security process.
"We are extremely upset and also disappointed that someone would steal it."
The 70-acre estate at Perry Green is home to the studios, barns and galleries gifted to the Foundation by Henry Moore.
The gardens house the late artist's sculptures.