A crazed teen gunned down a 15-year-old boy and a hero mom of eight just for being turned down from joining a casual game of soccer, according to cops.

Rafael Martinez-Lopez, 18, allegedly pulled out a gun and shot young teen Jeremiah Griffin-Cuevas in a fight over the game at an elementary school in Grand Rapids, Michigan — then also killed mom Savanah Villarreal, 39, when she tried to help.

“She gave her life to save my son,” Griffin-Cuevas’ mom, Mildred Griffin, told Fox 17 through tears.

The suspected killer was busted at home after fleeing the bloodbath — which was witnessed by at least eight horrified kids, cops said.

Jeremiah Cuevas-Griffin, 15, considered Villarreal his “auntie.” GoFundMe

“A bunch of kids were playing at the park here, and the suspect approached, asked to engage in a game of soccer,” Grand Rapids Interim Police Chief Joe Trigg told WOOD-TV .…