Fire crews were called to Woodside in Thornwood at around 8.50pm last night.
Essex County Fire and Rescue Service attended and extinguished the blaze, but sadly two horses perished.
No people were hurt, and Essex Police is treating the fire as suspicious and has launched an investigation.
Witnesses or anyone who was in the area around the time and saw any suspicious behaviour are asked to contact Loughton CID on 101 or independent charity Crimestoppers anonymously on 0800 555 111, quoting incident 1159 of 8 September.
