Police said they were forced to use pepper spray to break up a fight between two parents in a school playground.
Children at Penryn Infant School looked on "frightened" as officers blasted the man involved with captor CS spray, similar to pepper-spray, after the altercation at the end of the school day, reported The West Briton.
Police were already at the school after a "full-on fight" between two mothers earlier in the day, according to the local newspaper. But police were forced to take action after another fight broke out later in the day.
One parent who witnessed the second scuffle told The West Briton: "It was horrible.
"We were all shaking and I was in tears when I got home. Lots of other mums said their children were too upset and having nightmares to go back the next day."
PC Jules Evans said: "We went to prevent a breach of the peace, but the male involved would not heed advice and became very aggressive and assaulted another parent.
"As a result of his behaviour we were forced to use the spray and physically restrain him."
A spokesperson for the Devon and Cornwall police told the Huffington Post UK: "The use of CS spray is an effective tool for officers particularly in public order and violent incidents in order to prevent escalation of an incident to bring it to a swift conclusion and prevent injury to victims and innocent members of the public. "
One man was arrested and has been released on bail, pending further inquiries.
Head teacher Gillian Wright wrote to parents after the incident.
"Children who are very young have witnessed something they never should have," she said.
"That behaviour should never have happened. Safety and happiness are the most important things for children at the school.
"It is still awful, but if I had to call the police and wait for them to arrive it could have been so much worse."
It's not the first time CS spray has been used in a school environment. Police officers giving a 'respect' talk at a school in Northampton caused a storm after using pepper spray to break up playground scuffle between two 15-year-old pupils.
Police said they used the spray, despite no punches being thrown, because physically separating the boys could have "dislocated their shoulders or broken their arms" reported the Daily Mail.