Two people have been left seriously injured and a further 20 hurt after a train carrying around 150 passengers derailed in extreme heat in East Sussex. Now experts suggest that soaring temperatures may have caused the tracks or embankment beneath them to buckle.The eight-carriage Southern service came off the tracks between Haywards Heath and Lewes at around 3.54pm on Thursday, with three carriages overturning and passengers forced to scramble out of the wreckage as temperatures climbed above 35C.South East Coast Ambulance Service confirmed that around 150 people were on board the train, while adding that two people were rushed to the major trauma centre with 'severe' injuries, and a further 20 patients were also treated with minor injuries. Three air ambulances and at least 20 other emergency vehicles raced to the scene, while a number of passengers who did not require hospital treatment were taken to a local community centre to be triaged and supported.Pictures from the scene show passengers standing on top of the overturned carriages, with emergency crews including Sussex Police, British Transport Police, paramedics and East Sussex Fire and Rescue Service rushing to help those inside.The cause of the derailment has not been confirmed, but transport experts have raised the possibility that the exceptional heat contributed to the crash by causing the rails to buckle or the dry ground beneath them to collapse. Experts suggest that soaring temperatures may have caused the tracks or embankment beneath them to buckle before the train derailment in East Sussex The eight-carriage Southern service came off the tracks between Haywards Heath and Lewes at around 3.54pm, with three carriages overturning A passenger train has derailed near Lewes, leaving dozens of people trapped in overturned carriages One passenger appeared to be being taken away by emergency staff on a stretcher