A man has been arrested after more than a dozen sheep were killed when two dogs got into a field.
The dogs were seen chasing sheep in a field near Much Hadham in Hertfordshire at about 05:40 GMT on Sunday, police said.
Thirteen sheep have been confirmed dead and six are injured.
The man, who was arrested on suspicion of having dogs dangerously out of control and sheep worrying, has been released under investigation.
The two dogs remain in police care, Hertfordshire Police said.
East Hertfordshire Ch Insp Gerry McDonald said: "We understand this is an emotive issue and we recognise the impact it can have on our rural community.
"We are doing everything we can to investigate this matter so that where appropriate charges can be brought against anyone found to be responsible."