"She came running over here to tell the police that someone stabbed her, and they all told us to just turn around," said Marina Ramirez, a student who was watching the K-9 demonstration.
The woman told deputies three brothers were fighting in the backyard of her house on Bliss Avenue. When officers tried to separate them, the men turned their anger onto the deputies.
"The brothers are really trying to stop the guy with the knife. They don't want him to do anybody else any harm," said Tony Botti with the Fresno County Sheriff's Office. "When our deputies get there and intervene, they get amped up and upset, trying to protect their other brother."
Detectives were able to pull off the first brother quickly. The second one struggled with officers and was bit by a canine. The third brother, the main suspect, was the most combative with his knife.
"We fully believe that he was under the influence of something," said Botti. "He was showing incredible strength, he was showing that he was just not right."
Deputies say 26-year-old Edson Sandoval not only injured his brothers but also stabbed his own mother in the stomach. Officers still don't know what caused the family to fight.
"Thank goodness we had our deputies in the right spot and the right time, doing good community service work, putting on a canine display for the kids. It was Johnny on the Spot," said Botti.
Deputies say if it weren't for the school assembly and having a K-9 on hand, the Sandoval brothers' wrestling match could have had a very different outcome.
Two of the brothers are now facing multiple felony charges including battery on an officer.