PHOENIX - Family member of a 1-year-old who was hit and killed by a truck Tuesday night say the boy snuck away during a party.

Phoenix police say a pickup truck driver accidentally backed over Xavier Hernandez. They said the driver is cooperating with police.

"Everybody was just celebrating and having a good time," Xavier's great-aunt Andrea Longoria said. "Sometimes things happen and unfortunately it was one of those situations."

"He (Xavier) was the light of their life," Longoria said.

Neighbor Hector Torres said he saw the accident happen.

"No matter how old the child is or how young, you should never take your eyes off the child," Torres said.

Xavier's family has set up a GoFundMe account to help with funeral expenses.