The charity's CEO Patrick Green said there had been extra funding to tackle knife crime, which he welcomed, but added that the government needed to act with more urgency and that budget cuts affecting youth services had played a part. "She didn't know what to do".
The woman, who did not want to be named, said it only became clear the teenager had been shot when paramedics removed her bra to get to her injury.
"I tried to save her at the time".
Describing the victim as a "good girl", she said: "She didn't deserve that".
"Victim 1 remains in a critical condition and Victim 2 has life-changing injuries but not life-threatening", the police said.
Police said they were called to the hospital just after 8.30pm on Thursday and officers have designated it a crime scene while they examine the vehicle used to transport the victim.
Joshua vs Parker: Dillian Whyte interested in fighting Alexander Povetkin
There is a rematch clause for the fight, but Joshua's promoter, Eddie Hearn , said that would not be happening. Anthony Joshua defeated Joseph Parker by points on Saturday to unify the WBO belt to his IBF and WBA titles.
Cops confirmed this morning there has been no arrests and they do not believe the shootings to be linked.
A third incident on Sunday evening left a 16-year-old boy in hospital after he was stabbed near Bow in east London.
Metropolitan police commissioner Cressida Dick, Britain's most senior officer, said that police alone would not be able to halt the trend, pointing the finger at the use of social media by youngsters.
A Sunday Times report found England's capital recorded 15 murders across the month, which was one victim more than NY.
It is the latest in a string of fatal stabbings in London and comes just days after two men were knifed to death within 12 hours of each other in the city. "It's looking like it'll be worse that last year, which was worse than the year before", he told Reuters.
A Downing Street spokesman said that the Government's new serious violence strategy will focus on intervention measures meant to "break the cycle" of violent crime. "They do not obey the laws against guns, knives or murder and mayhem".
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