Over the past few months, the British government has been heavily criticized for cuts to the budget of police forces across the United Kingdom, with many blaming these austerity measures for the increase in violent crimes.
No arrests have yet been made and no firearms have been recovered.
They came one day after a 19-year-old was fatally shot in Southwark in South London, around 11 and a half miles (18.6km) away.
Police officers were called to reports of gunshots on Cooks Road in Southwark at 6.05pm on Saturday. His conditions is also not life-threatening.
"A 12-year-old boy was treated at the scene before being taken to a west London hospital where he remains now", it said in a statement.
"We're not being protected because of the police".
And detectives today issued an appeal for witnesses after a 43-year-old man was stabbed on a street in Perivale. His condition was initially deemed critical, police said, but is now thought to be not life-threatening.
Soldiers rescue 1000 Boko Haram hostages in Borno
Nigerian President Muhammadu Buhari said earlier this year that the era of Boko Haram violence "is gradually drawing to end". Exactly a year ago, the Islamic jihadist group Boko Haram released 82 of the 276 schoolgirls it had taken by force in 2014.
The teenagers were shot less than 24 hours after Rhyiem Barton, 17, was shot dead on Saturday.
Three men aged 22, 27 and 17 were also injured in a "noxious substance" assault following an altercation between two groups in Hackney, east London.
Police said: "At this early stage, it is believed that two male suspects riding one moped shot the victim".
A spokesperson for the Metropolitan Police said that a 15-year-old teen and a 12-year-old boy suffering from gun wounds were treated by an ambulance at the scene before being transported to a hospital for further medical treatment. "Officers retain an open mind as to any motive". A man was arrested on Sunday in connection with the two Harrow attacks and has been released "under investigation".
Officers have been made aware of a possible third victim who may have been at the scene with the 15-year-old.
Official statistics released in April show the number of homicides in London has spiked by more than 44% in the past year.
Outside the capital, two men died in stabbings in Liverpool and Luton during the bank holiday weekend. The strategy is to be backed by £40m of Home Office funding and a new offensive weapons bill to ban the sale of corrosive liquids to under-18s and introduce tougher restrictions on buying knives online.