More than 30 cars have been badly damaged following an attack at a garage in the early hours of Thursday 2 May.
Mark Chalk, owner of Babylon Motors, on Babylon Hill between Yeovil and Sherborne, was shocked to discover what he describes as "a mindless act of violence" on his forecourt.
A total of 30 cars have had their windows smashed, while around nine have suffered paint and body damage.
Dorset Police were called at 2.44am, by a member of the public reporting "suspicious activity".
Mr Chalk believes the perpetrator wanted to cause "lasting damage".
It wasn't someone who has just done it in a couple of minutes; you'd expect if it was someone who was angry at us they would have done one or two and ran away, but this is someone who wanted to do lasting damage.
Mr Chalk says that at around 2.30am someone passed by the garage and all of the alarms were going off. A young man, who may have been between aged 20-30, was reportedly seen running away.
Paint and body damage has been caused to about nine cars and 30 have had their windows smashed.
Mr Chalk estimates that the cost of the damage is about £15,000 and says that despite the garage being fully insured, the business will still suffer as the result of the attack.
We're insured but we are going to facing a 5-10 day slow down to business definitely.
We're offering a £1,000 reward to anyone with information that will help lead to an arrest.
Police received a report at 2.44am on Thursday 2 May 2019, reporting suspicious activity at the Babylon Motor Centre at Babylon Hill.
Witnesses or anyone with information is asked to contact Dorset Police on 101.