Two fires that destroyed 19 homes in Stourbridge were started accidentally in fields where farming machinery was in use, according to West Midlands Fire Service.
Investigators established farming equipment was being used in the vicinity of fields immediately before the fires were first reported.
The first fire started in a field near Racecourse Lane at about 13:27 BST on 13 August, while a second began shortly afterwards in a field near Quarry Park Road.
The day after the fires the government sent out an emergency alert to millions of people across England and Wales, warning them against “any activity that could start a fire”.
Justifying why the alert had been sent, Prime Minister Andy Burham said: “I was in Stourbridge today and saw first-hand the devastating impact these fires have had on people’s homes and lives.”
West Midlands Chief Fire Officer Simon Tuhill said at the time the Stourbridge blaze was one of the most significant incidents the service had ever dealt with.
He said on Wednesday so many people had been affected he wanted to confirm both fires were not started deliberately. They were accidental, he said.
“While investigations continue into the full circumstances of what happened, we wanted to share this latest update as soon as possible,”Tuhill continued.
“I hope it will go some way towards helping people understand what happened on that exceptionally hot and challenging day.”