Last updated at 00:37 11 May 2008

A gang of teenage girls may have blown up a house with a home-made liquid bomb, which killed a man in a neighbouring property, after arguing with another girl about a love rival.

Purple liquid was poured through the letterbox of the Victorian house before the an explosion destroyed three houses.

Their intended victim, Charlotte Anderson, was caught in the blast and was rushed to intensive care suffering with severe burns.

Ten hours earlier Miss Anderson had phoned police to say a gang of girls aged 16 and 17 was causing trouble outside her home, in Harrow. They were directing abuse, about a boy, at Miss Anderson's ground floor flat.

Scroll down for more...

Devastation: Three houses weer destroyed in the blast, and one man was killed

Witnesses said they saw someone pouring a "purple, smelly liquid" through the letterbox of the house.

Experts say the liquid could have vaporized and caused the explosion, which killed Emad Qureshi, 26, who was at home with his parents in a neighbouring house at the time of the blast.

He was crushed to death by falling rubble.

Miss Anderson was pulled from her wrecked flat by a neighbour and she was rushed to hospital, where her condition was described as "non life-threatening".

Scroll down for more...

Explosion: The massive blast destroyed three houses

Scotland Yard launched a murder investigation and is hunting the girl gang.

A police source said the liquid could have been made using a "recipe" found on the internet

DCI Colin Sutton said: "Our major line of inquiry is that this liquid caused the explosion and that the explosion was an attempt to murder this young woman."

Police originally thought the devastating explosion had been caused by a gas leak, a theory which has now been played down.

DCI Sutton said: "We still haven't ruled out a gas explosion but experts say it is unlikely to be the cause. What we can say is that we are happy there is no link to any terrorist organisation or acts here.

"A strong line of inquiry for us at the moment is the dispute, this call at the address and of course the substance that was put through the letterbox."