Six people have been arrested after armed police were called to a primary school when a fight between men armed with weapons spilled into the grounds.
Several men had sharp objects when they were close to Berwick Hills Primary School in Middlesbrough, police said.
The school grounds were immediately locked, and parents waited outside for news.
Four people were arrested at the scene and two were arrested later over a burglary thought to be linked to the fight. All six are still in police custody.
Two members of the public stepped in to help police arrest the suspects near the school, leaving one man suffering minor injuries. He was treated in hospital.
Cleveland Police said officers who were called to the school at around 8.40am had found a number of men with sharp objects.
Detectives later took away a large knife from the scene.
Headteacher Tessa Smith said: “As soon as we became of aware of an incident in the vicinity of the school, our emergency response measures ensured the site was secured with immediate effect.”
A number of parents remained outside the school while it was in lockdown, according to Teesside Live.
Detectives believe the fight near the school was linked to an incident two hours earlier, in which an aggravated burglary was reported to have been carried out at a property in Ellerby Green.
Four men threatened the occupants with a weapon, and a Vauxhall Insignia and a motorbike were stolen. The six arrested are aged 22, 26, 26, 27, 28, and 49.
A police spokesman said: “Officers can assure parents that the incident is not linked to the school, and officers will remain in the area for some time to provide a high-visibility presence and reassurance to members of the public.”
Ms Smith added: “I’d like to reassure parents and the wider community that at no point were any pupils at risk, and that staff acted with the utmost professionalism.
“I’m also grateful to Cleveland Police for their swift response in bringing the incident to a close.”
Additional reporting by PA