Doctors are battling to save the legs of a seven-year-old boy crushed under a tram during a horrific accident during the school run on Monday.

Screaming parents and children could only watch in horror as the child escaped the grasp of a woman - believed to be his mother - before being struck by the 36-tonne vehicle at the Fieldway tram stop in New Addington.

Firefighters were forced to use industrial jacks to lift the front of the Croydon-bound tram from the child, whose lower legs were trapped in the 4cm gap between the carriage and the rails.

Several witnesses reported the boy ran into the path of the tram to pick up a lunchbox he dropped while crossing the tracks with the woman and a younger girl, believed to be his sister.

Doctors at St George’s Hospital, Tooting, have spent the last two days performing a string of operations on the boy’s lower legs in an attempt to save them.

Medics from the Surrey Air Ambulance anaesthetised the child at the scene before treating his wounds, having made an emergency landing on the neighbouring Addington Court golf course.

He was rushed by ground ambulance to St George’s following the accident, which happened just after 8am.

Student Loren Pereira, 22, was among the crowd of traumatised onlookers who saw the boy crushed by the tram during the morning rush-hour.

Miss Pereira said the woman had tried to grab the boy back but he apparently panicked and rushed forward.

She said: "Everyone was just screaming. As the tram hit him he went straight under, his arm went up. Everyone thought he had died.

"But we heard him screaming and that's when we knew he was alive."

She said the woman ran over to the tram and held the trapped boy's hand.

Miss Pereira said: "She was traumatised by it."

Mum Esther Dorho was with taking her young son out for his birthday when the terrifying accident happened in front of her.

She said: “It was horrifying - the whole incident will stay with me for the rest of my life.”

The tram service was suspended between Addington Village and New Addington for much of the day.

A Tramlink spokesman said they would be investigating the incident.