A 75-year-old man is in a critical condition in hospital after he was trampled by his own herd of cows that became spooked by the siren of a fire engine.

Harold Lee was moving his herd of dairy cows from Robin’s Farm in Burtle, Somerset, along a B road to the milking parlour on 11 August with his son Richard, when they were approached by a fire engine answering an emergency call.

Richard, aged 42, who was leading the herd, said that he initially asked the driver of the emergency vehicle to turn off the siren while they calmed and moved the cattle, but the request was refused and the cows became so agitated by the sound of the siren that they stampeded back towards their field.

Mr Lee had been on a quad bike at the back of the herd but dismounted to try and calm the cattle down. However he was trampled in the stampede and suffered serious injuries to his head and chest.

Mr Lee was airlifted to Royal United Hospital in Bath, from where he was later transferred to Frenchay Hospital in Bristol. He is now fighting for his life and remains in a critical condition.

Richard who runs the farm with his father said: “It’s not far along the road from the field to the farm and father has made that trip every day for 50 years with no problems. We understand they were trying to get to an accident but there was no need for them to have their sirens going. Without that and the lights this wouldn’t have happened. We are all devastated. ”

He added: “When the driver saw what had happened and the blood on the road he got out to help. The doctors say that father is critical but stable. He is not conscious at the moment because he has been sedated and it is still very early days.”

A spokeswoman for Devon and Somerset Fire and Rescue Service confirmed that their fire engine had been involved in the incident but refused to comment any further.

An Avon and Somerset Police spokesman said that the incident was under investigation and the possibility that the cows were spooked by a fire engine is one line of enquiry.