London Fire Brigade investigations officer Matt Cullen said 21 firefighters and four engines responded to the apartment building fire Wednesday night and the nine people inside the building were able to escape without injury, the Daily Telegraph reported Thursday.
"When we got up into the roof, we were baffled as there were no obvious ignition sources," Cullen said. "No one had been up to there for a long time and there were no electrics that could have sparked a blaze. We looked everywhere, but the smoking gun was found when we discovered a partially burnt birds' nest. Neighbors told us they often saw birds flying in and out of a hole in the roof."
"We believe that one of the birds picked up a cigarette butt that was still smoldering and dropped it into the nest, causing it to catch fire and set the roof alight," he said. "The incident is a great example of why it's important to put your cigarettes out fully. You never know what might become of your smoldering butts.