Firefighters are investigating whether soaring UK temperatures contributed to a fire that engulfed a bus on a south London high street.

       The double-decker was seen covered in flames and black smoke on Christchurch Road in Streatham Hill on Friday morning.

       There had been close to 20 further calls about the incident following this initial alert. The London Fire Brigade confirmed that it responded to the blaze and confirmed all passengers and the driver were able to get off.

       It was not currently clear how many people had been on the bus when it caught on fire.

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       The A23 on Brixton Hill is blocked between New Park Road and the A205 South Circular.

       Onlookers stood in shock at the bus as smoke filled the high street before the Fire Brigade attended the scene just before 10am.

       A witness to the terrifying incident posted an image on Twitter, accompanied by the caption: “Well this is frightening!

       “Bus in Brixton pulled into the stop and promptly caught on fire. Huge flames & crashing as bits of it were burned off.”

       Photos following the blaze show significant damage to the back of the bus and upper-deck where windows can be seen broken and hanging off as well as the entire rear of the bus scorched.

       A London Fire Brigade spokesperson said investigators are probing the cause of the fire, including whether it is related to the hot weather in London.

       The bus suffered significant damage

       (Supplied - sademerrett)

       Another witness recording the incident added: “We were all panicking, I saw the fire from my window and ran into the street in case it exploded.”

       Marlon Osborne, Head of Operations at TfL, said: “The incident on a bus in Brixton this morning must have been really frightening for those involved. Thankfully all passengers were evacuated and there are no injuries. We are working closely with the emergency services and the operator to urgently investigate what happened.”

       In a statement the Brigade said: “Firefighters were called to a bus alight on Christchurch Road in Streatham Hill.

       “Part of a double decker bus was damaged by fire. The driver and passengers left the bus before the Brigade arrived. There were no reports of any injuries.

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       “The Brigade’s 999 Control Officers took 19 calls to the blaze.

       “The Brigade was called at 9.50am and the fire was under control by 10.22am. One fire engine from Brixton Fire Station attended the scene.”