Jacueline Solis rode the pink and purple bike into the truck's path as it accelerated from a stop at an intersection, police Sgt. Charlie Delgado said. Jacueline, who got the bike as a Christmas gift, died at the scene.
The driver was not speeding and won't face criminal charges, police said.
"She was only supposed to ride on the sidewalk," said Maria Guerra, Jacueline's aunt.
More than 50 people held a candlelight vigil in Jacueline's memory Tuesday evening.
"She was just out caroling up and down this street last night," said Raul Guerra, the uncle of the girl's father. "She knew about everybody on this block."
The family was in shock over the loss and dreading future holidays. "They'll be so difficult for us," Raul Guerra said. "I don't know how we'll do it."