The teenager was described by those who knew her as a "lovely girl who minds her own business", a "kind beautiful young soul" and an "innocent kid".
Her cousin tweeted: "Rest in perfect peace my cousin Tanesha."
A friend wrote: "Omggggggggg , not Tanesha Lord ! I literally watched this girl grow".
Members of the community spoke of their shock at the death, tweeting that they were "lost for words" at the "senseless death".
Tottenham-raised rapper Wretch32, whose real name is Jermaine Scott Sinclair, tweeted: "Wish I knew what to say about what's happening in my ends. North London we're better then this man smh R.I.P to the young angel who lost her life last night. love & prayers to the family. I'm honestly lost for words."
The witness in Tottenham said: "Her friend came banging on my door so I came out quickly. I even tried to save her - had to, had to."
She said the gunshot wound, below the victim's breast, was not immediately visible and it looked like she was "having a fit".
"I put her on her side and I was just rubbing her back, saying 'everything's going to be OK'. I just can't believe it - so young. It's ridiculous now."
The woman said the victim was not responding, but added: "I could see she was looking at me."
She told how the girl's mother arrived before paramedics, adding: "She was screaming. She didn't know what to do."
In the second shooting, a 16-year-old boy was found with gunshot injuries in Walthamstow.
Police and London Ambulance Service said they were called to reports of gun fire in Markhouse Rd.
The boy was in a critical condition at a hospital in east London, according to police. Sky News now reports that he has died in hospital.
A second teenage boy was also being treated for stab wounds. Police said he had suffered life-changing injuries but they were not life threatening.
Stella Creasy, the local Labour MP, tweeted: "Walthamstow - can confirm tonight we have had another serious incident involving shooting and stabbing.
"Appreciate this is very distressing- I will share more information as and when have it from official sources as only want to share what is confirmed."
The shootings come amid concerns over rising violent crime in the capital.
On Monday a 20-year-old man became the 31st victim of knife crime in London so far this year.
He was fatally stabbed moments after leaving a bar in Wandsworth and died in the street.
Last Friday the family of Abraham Badru, 26, who was shot dead down in Hackney, east London on March 25, warned that "gun culture is becoming rampant in our community".
London has seen more murders committed during the past two months than New York, which once had a fearsome reputation for violence.
In February, London recorded 15 homicides compared to New York's 14. In March there were 22, as opposed to 21 in the US city.
