A convicted gang member was sentenced to nine years in state prison Friday for an April 2012 attack at Steelhead Beach on the Russian River west of Windsor, District Attorney Jill Ravitch said.

Alejandro Guadarrama, who was 20 at the time of the attack, joined two friends to assault and seriously injure two people at the popular beach, which is frequented by families, Ravitch said.

He was convicted and originally sentenced to the nine-year term in 2012 after pleading no contest to a charge of felony assault with a bottle with a gang-related enhancement, Ravitch said in a written statement.

At the time, the court took a chance by suspending the prison term and granting him probation, she added.

"While on probation the court gave him several opportunities to change his life and reject his gang involvement," Ravitch said. Despite that, he violated his probation by using illegal drugs, participating in gang-related activity and more, Ravitch said.

Guadarrama was also ordered Friday to pay more than $3,700 in restitution to the victims, who had to be treated at a local hospital.