He ran to Stapleton Road – where a driver helped him – before he collapsed on West Street.
Ambulances were called but he died at the scene, police said.
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A 16-year-old boy has died after being stabbed in Bristol
Supt Mark Runacres, Avon and Somerset Police’s Bristol Commander, said: “The team investigating yesterday’s incident are working around the clock to bring those responsible to justice.
“This evening, two 15-year-old boys were arrested in connection with the investigation and they have been taken to police custody where they will be questioned.
“Our collective thoughts are with the victim’s family and loved ones during what is undoubtedly a very difficult time.
“Specialist family liaison officers have been assigned to the family to provide them with support and keep them updated on the investigation.”