Three horses have died in an incident on the Ballyrobin Road near Belfast International Airport.
It follows reports of horses loose on the carriageway on Tuesday evening.
The animals were filmed trotting near the entrance to the airport close to the Maldron hotel.
Police closed the road for almost two hours while they dealt with the incident.
A PSNI spokesperson said: "The road was closed for a short time whilst officers cleared a number of other horses from the carriageway but has since re-opened.
"Enquiries into this incident are ongoing."