Thousands of pounds worth of damage was caused by arsonists after they torched crops on a farm near Middlesbrough.
A tractor and 30 acres of crops were destroyed in the blaze at Newham Farm, Coulby Newham, at about 12.45pm on Sunday, July 16.
It is believed a group of youths are responsible for the attack.
Detective Constable Joanne Williams, of Cleveland Police, said: “This fire has had a devastating impact on the owners of the farm and has caused significant damage, leaving crops and a tractor completely ruined.
"Luckily no one was injured but this fire could have easily escalated, resulting in someone being severely injured or even killed.
“We believe that a group of youths are responsible for the fire and therefore we would appeal to parents to ensure that they know where their children were when the incident happened. Arson will not be tolerated and immediate action will be taken against anyone involved in this incident.”
Phil Lancaster, Director of Community Protection at Cleveland Fire Brigade said: “Make no mistake, deliberate fire setting is a blight on the whole community. Fires such as these can cause serious damage and divert our resources away from real emergencies.
“Fires of this nature are extremely dangerous and while to young people setting fires in fields may be seen as harmless, the flames can spread very quickly and can have deadly consequences. Once again we ask parents to make sure they know what their children are doing and make sure they are staying out of trouble.”