A fire which started in nearby fields spread to a residential area and destroyed buildings and gardens.
One elderly woman was seen crying hysterically saying: “Oh my God – the house is gone”, while her family tried to comfort her.
Black smoke billowed into the air in the east London village and a rescue centre was set up for residents at a nearby Premier Inn.
Meanwhile, across London blazes damaged houses, schools and churches with fire crews describing the scenes as “absolute hell”.
Several other significant incidents also occurred, with people urged not to have barbecues or bonfires due to the “unprecedented” challenges crews faced.
What happened in Wennington?
Two “large-scale” incidents took place in Upminster and the village of Wennington, east London, where black smoke billowed into the air.
A firefighter at the scene in Wennington told the PA news agency that conditions were like “absolute hell”.
Those affected by the blaze said it had been spreading “fast”.
Residents could be seen being comforted, while others were seen removing gas canisters from a nearby pub, as hundreds of firefighters were at the scene.
At least one home could be seen completely destroyed by the fire, while others appeared to be badly damaged
Local resident Janet Hickey, 70, who has terminal pancreatic cancer, said she was forced to leave all her cancer drugs behind as they were evacuated.
Her husband Patrick Hickey, 71, added: “We had to leave everything.
“We’re hoping against hope that our house is still there.”
Riminta Maceikaite, 38, and her son Nikas Janulevicius, 13, said their neighbours’ homes have burned down but as far as they can see from TV aerial shots, their house is still standing.
Lizzie Pittman, from Aveley in Essex, who works at some stables by the roundabout, said she was looking after five horses that were evacuated.
She said: “This is your worst nightmare.
“You can see it getting closer and closer.”
She added: “People are losing their houses but that’s bricks and mortar.
“People are losing their livestock.”
Nearby resident, Lynn Sabberton, who said she was evacuated from her home with her partner who has a lung difficulty, told Sky News: “I saw the black smoke and the helicopters came over and more police came into our neighbourhood and it was really spreading very fast.
“It just spread so quickly, I think the wind caused the fire to go our way towards the village.”
The Premier Inn, which was set up as a rescue centre for residents, also lost power for around an hour.
One fire official told the PA news agency the fire may have hit the main power line.
Later, residents who were at the Premier Inn were advised to find alternative accommodation for the evening.
A rest centre was set up at Hornchurch Sport Centre where air mattresses have been provided.
Andrew Blake-Herbert, Havering Council chief executive, said: “We need people to avoid the Wennington area if at all possible and need local people to keep doors and windows closed to protect from smoke and ash.”
How many fires were there in London on Tuesday afternoon?
Among the fire which started in Wennington, there were many other incidents across the capital.
- 30 fire engines dealing with a grass fire on Pea Lane in Upminster.
- 12 fire engines tackling a fire involving garden fencing and trees on Uxbridge Road in Pinner.
- 10 fire engines tackling a restaurant fire on Green Lanes in Southgate.
- Eight fire engines tackling a grass fire on Oaks Road in Croydon.
- Eight fire engines tackling a grass fire on Ballards Road in Dagenham.
- Eight fire engines tackling a fire on The Broadway in Wembley.
- Six fire engines tackling a grass fire on Sunningfields Crescent in Hendon.
- Four fire engines tackling a grass fire on Chapel View in Croydon.
- Four fire engines tackling a fire on Sidcup Road in Eltham.
What other incidents happened in London due to the heatwave?
In London residents were evacuated from their homes and people were taken to hospital amid fires as temperatures soared to more than 40C on Tuesday afternoon.
Houses were evacuated in Dagenham following a “significant grassfire” which affected a number of buildings.
Two people were also taken to hospital suffering smoke inhalation - with the full number of casualties currently unknown.
Fires were also seen next to a motorway on Dartford Heath.
Liam Edwards, 25, from Bexley, a student at Oxford Brookes, spoke about the fire by the A2 in Dartford.
He said: “It was huge when we left it multiple fire engines I’d like to say it’s under control but who knows at this point?
“I’ve lived in London and Kent all my life I’ve never seen anything like that before.”
Sadiq Khan said London Fire Brigade (LFB) had received more than 1,600 calls for assistance by late Tuesday afternoon.
Jonathan Smith, assistant commissioner at LFB, told the PA news agency: “We’ve had a range of incidents today, obviously a number of which have been the result of the tinderbox dry woodland and grassland both in central London and in the suburbs.
“This has caused rapid fire spread which has impacted on properties, people’s homes, schools, churches and other types of buildings.”
Mr Smith added: “At the moment, because of the sheer number of incidents we’ve been attending today, we will be pulling all of that information together and making sure every incident is thoroughly investigated.
“Once we’ve done that we’ll be able to give an accurate picture of exactly the incidents we’ve attended, how many homes have been affected and if there have been any casualties.”
The London Ambulance Service said the total number of people taken to hospital may not be known until Wednesday morning.