Dorados de Sinaloa on Tuesday reported that one of their youth team players, Mirsha Francisco Herrera Gastelum, was stabbed and killed in the city of Culiacan, Mexico.
A source close to the club told ESPN Deportes: "The incident occurred between 11.30 a.m. and 12 p.m. He had got to training very early and left.
"Right after, we found out [about the stabbing] from the hospital because they recognised the kit and spoke to the club. They said: 'We have a player from your team here called Mirsha. It's all we know because he has nothing on him.'"
Left-back Herrera Gastelum had spent five years with the club, having joined them when he was 15.
He had already trained with the first team on several occasions while Diego Maradona was manager.
Herrera Gastelum has a brother, who plays for Xolos de Tijuana's under-17 side.