Roger Lord, of Earls Hall Farm, St Osyth, said caravan residents on the farm land passed police a picture of the suspected lion after photographing it.
The first thing we knew about it was a phone call from the police last night. I am sceptical - I think it might just well be a large domestic cat but they certainly saw something that they were were concerned about and they went down the right route to the police.
They have taken it very seriously and have put two helicopters up in the air and I don't know how many armed police that we still have on site now. They have taken it very seriously.
Most of the residents of the caravans were on site at the time of the sighting, he added: "I think most of them were on site at the time, so more than one person saw it."
A search for a lion in Essex has been called off, with police believing the rogue animal was most likely to be a "large domestic cat".
Police are responding to reports that a lion was seen in a field near the Essex village of St Osyth. Firearms officers have been deployed.