Police believe thieves may have received injuries during a break in at an electricity substation in West Yorkshire.
The attempted theft of cabling caused an explosion or electricity arc in the building on Hightown Road, Liversedge.
Those who broke in may have suffered burns, officers said.
The incident comes after the death of a 16-year-old boy at a substation in Stourton, and a gas explosion in Castleford linked to cable theft.
Anyone with information has been asked to contact West Yorkshire Police.
Insp Tim Holland said: "When these thieves have tried to remove the copper cable from the substation it appears that they caused an electricity arc or some sort of explosion within the building.
"It would therefore be a very lucky person who came away from something like that without any sort of injury.
"We would appeal for anyone who knows of someone who has suffered recent and mysterious burns or injuries to their hands or face, to call us."