Haltwhistle horse attacks: One dead in 'brutal' stabbing
One horse died and another was treated by vets after what police described as "cruel and brutal" stab attacks.
The horses were grazing in a field in Haltwhistle when they were targeted sometime between 8 and 10 July.
They were both treated by vets but one subsequently died from the injuries it received, Northumbria Police said.
A spokesman said both animals were stabbed "a number of times". The owner was too upset to comment.
The spokesman added: "This was a cruel and brutal attack on two defenceless animals and we are determined to catch those responsible.
"Both animals were stabbed a number of times and required two vets to work together on stitching together the wounds. They were surprised the horses were still alive.
"We suspect that whoever could be responsible for such an offence would have been in a group and would have been covered in blood following the incident."
Police have appealed for witnesses.