THE cause of a fire at an electrical substation outside a Helensburgh supermarket last week remains unknown, according to police.

Shoppers watched in horror after the blaze broke out in the unit at the car park outside the Co-operative Food store in Sinclair Street on Wednesday, sending plumes of smoke billowing over the town centre.

Police and firefighters rushed to the scene after the Scottish Fire and Rescue Service (SFRS) received reports of an electrical fire in Sinclair Street shortly before 4.30pm on April 28.

An SFRS spokesperson told the Advertiser that two appliances had attended at the scene and no casualties had been reported.

WATCH: Dramatic footage of electrical fire near Helensburgh supermarket

Inspector Roddy MacNeill from Police Scotland in Helensburgh said: “Officers and SFRS personnel attended the report of a fire within the electricity sub-station located in the car park.

“The area was cordoned off to allow the SFRS to extinguish the fire.

“The locus was stood by overnight by Police Scotland, and a joint investigation by police, the SFRS and Scottish Power was undertaken the following day to determine the cause.

“At the conclusion of the investigation it could not be confirmed that the fire was started deliberately.”