Police are investigating a fire at a car lot in Cleckheaton.
Crews from Dewsbury and Cleckheaton were called to the blaze at Trade Cars on Bradford Road in the early hours of Tuesday morning.
It is thought one of the vehicles caught fire and flames spread to three others.
Nobody was injured, although a security guard was on site at the time.
A police spokesman said: “We were called to the scene at 2.18am after reports a car and vans were on fire.
“Officers attended the scene and we are now investigating the incident as possible criminal damage.”