A 16-year-old Trinity School student has been left fighting for his life after an arson attack hospitalised him and claimed the life of his younger sister.

Junaid Masud and his sisters, Nabiha, 21, and 15-year-old Maleha – who died on Thursday – had to be rescued from the first floor of their Tooting home by firefighters wearing breathing apparatus.

Junaid’s mother, Rubina Masud, 53, and her eldest son, Zain, a 22-year-old city banker and a former Trinity School student himself, were forced to leap from a first floor window as the fire ripped through their home just before 4.30am on Sunday, June 21.

Mrs Masud said: “I am devastated at what has happened. I can’t believe anyone would do such a thing. I am just really concerned for my children, please pray for them.”

Junaid, who is said to be highly academic and wants to be a doctor, won a scholarship to study at Trinity School.

Headmaster of Trinity School, Mark Bishop, said: “Junaid is a bright and talented man from a very supportive family.

“The whole community at Trinity has been shocked to hear of this incident and our thoughts and prayers are with him and his family. Junaid is a genuinely charming, well-behaved and talented young man.”

A Met Police spokesman confirmed a murder investigation had begun following Maliha’s death.

Detective Chief Inspector Damian Allain said: “A mother has had her youngest child taken from her in the most tragic circumstances.

“Her three other children remain seriously ill in hospital. They were at the place where they should feel safest, in their family home.

“Whoever has committed this act is not only a coward but is a dangerous individual who must be caught.

“I would appeal to people who may have seen anyone carrying a petrol can or similar container to come forward."

Anyone with information should contact police on 020 8721 4805 or call Crimestoppers anonymously on 0800 555 111.

Three teenage boys, aged 17, 15, and 14, were arrested in connection with the incident.