A betting shop in Whitton high street was left gutted after an electrical fire severely damaged the property on Tuesday, January 28.
Nobody was injured in the blaze which started before 1pm but three people had to flee.
Lisa Hicks, station manager at Richmond fire station, said: "We received a call at 12.56pm to a fire in William Hill in Whitton high street.
"It was a severe fire when we arrived - there have been no injuries and the investigation has now started."
The crews worked for more than an hour to bring the fire under control.
One member of staff, deputy manager Mohammad Hassan, and two customers were in the shop at the time.
Mr Hassan smelled burning and evacuated the shop before calling the fire brigade.
Firefighters were called after Police Inspector Simon Young happened to be driving through the high street at the time.
Inspector Simon Young said: "We made some attempts to put the fire out.
"We ran round to the back of the property in order to go up to the flat to make sure nobody was in danger.
"When we were satisfied that was the case we assisted by putting road blocks in place."
Anish Gola, 34, assistant manager at Your Move which is next door to the bookies, said the police came into the shop to see if anyone was in the above flat.
He said: "Police said it was an electrical fire and we all just stood outside on the high street.
"The smoke got darker and darker - one of the firefighters knocked some of the windows through to check if anyone was in there."
Mustafa Yaqub, 27, who works at Whitton Car Audio on nearby Bridge Way, said: "I was working outside my shop when I saw smoke from the windows.
"I ran across and saw a big fire so I went across the road and started filming.
"Everyone seemed to get out pretty quickly."
A witness who asked not be named said staff at neighbouring Subway were concerned because the fast-food outlet uses gas cookers.
A William Hill spokesman said it would be a "considerable amount of time" before the shop opens again and staff would be relocated to other branches.
They added the flat above the shop, close to Whitton station, had been gutted also.
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Video courtesy of Sam Maywood.