A murder investigation has been launched after a 16-year-old boy was stabbed to death.
The teenager was attacked before 18:00 GMT on Wednesday by two people wearing masks in Rawnsley Park in Bristol.
The victim ran to Stapleton Road, where a motorist assisted him, before he collapsed in West Street, Old Market, and died at the scene.
Police officers had enhanced stop and search powers authorised for 24 hours from 17:00 on Thursday.
This allows them to search people for weapons without needing reasonable suspicion, and ask them to remove any face coverings.
While formal identification of the victim has not yet taken place, Avon and Somerset Police (ASP) said his family had been informed.
Shop workers Essie Zadeh and Anne Pashaliska said they saw a van pull up to help the teenager, who was lying on the ground.
Ms Pashaliska said: "The boy was moving hectically, he was covered in blood so I called 999.
"They asked me to take a piece of cloth and try and stop the bleeding."
"It is shocking, he was a really young boy. Really sad," she said.
'Horrific circumstances'
In a statement, ASP said the attack was a "stark reminder" of the "horrific impact" knife crime had on communities.
Supt Mark Runacres said: "Tragically, we have lost another young life from our city in utterly horrific circumstances.
"Our thoughts are with the victim's family at what will be an unimaginably difficult time and officers will continue to support them."
He said the force was "keeping an open mind" but there was "no clear evidence to suggest this is linked to other recent incidents in the city".
Police and Crime Commissioner Mark Shelford said he would be arranging a meeting between police and community leaders "to share information about what is happening and next steps".
"I have asked the Chief Constable to explore the full range of practice options that the police have at their disposal for prevention and deterrent, and to explore options of bringing into the force psychologists and academics to audit the best practice for the prevention of knife crime," he added.
Bristol Mayor Marvin Rees said the death was "tragic news".
"I can't begin to imagine what the victims' family are experiencing, my thoughts are with them," he wrote on social media.
"This needs to stop. We will make every effort to support the family, the police and local community at this time," he added.
ASP said there would be increased patrols in the area as officers made enquiries.
A post-mortem examination will take place in due course, police said.
