The older boy died at the scene and the younger boy died while being rushed to a hospital, police said. Their names were being withheld because of their age.

“How do you just kill kids?” a mother, whose son was a schoolmate of one of the deceased boys, told KGO-TV. “I don’t think he has quite grasped this yet,” she said of her son. “He is afraid to go outside.”

While it was unclear which schools the boys attended, New Haven Unified School District Superintendent John Thompson confirmed they attended schools in the district.

Family and friends set up a makeshift memorial at the school as police collected shell casings and other evidence for their investigation, KGO reported.

No arrests have been made in connection to the killings. Police said they were still investigating a motive for the shooting.

The possibilities that the shooting was gang-related or related to a previous shooting on Wednesday that left two men wounded have not been ruled out, police said.

Police Lt. Steve Mendez told the Times that there was no sign of a connection between the shooting and the school where it took place. He said people occasionally gather in the relatively secluded parking lot.

The Associated Press contributed to this report.