A nine-year-old boy has described witnessing Monday’s deadly shooting at the Islamic Center of San Diego, saying that he “saw bad stuff” and huddled in closet during the attack.

Odai Shanah, whose mother emigrated from war-torn Gaza and settled in southern California two decades ago, told Reuters that he heard a barrage of gunshots coming from outside the walls of the mosque complex, which also houses an Islamic day school.

He recounted being among dozens of children forced to huddle in classrooms when deadly gunfire erupted at the mosque.

Shanah said he and his classmates were trembling in fear as 12 to 16 more shots rang out after they were quickly ushered into that closet and crowded there together.

After the shooting stopped, the boy said, he and his companions heard members of a special tactical police team shouting from outside the classroom: “‘OK, open up,’ then they opened the door.”

But as they were escorted out of the building, “we saw a bunch of bad stuff, people laying down and yeah, bad stuff,” Shanah said. He acknowledged meaning that he and the other children had seen bodies as they walked out in “a big line” with their hands up.

“My legs were shaking and my hands and my head were like hurting a lot,” he said. “I felt like a rock.”

Shanah gave Reuters his heartbreaking account of the shooting after permission was granted to the outlet by his parents.

It was a stark reminder of how youths in the US are disproportionately affected – whether directly or indirectly – by gun violence, which is the country’s leading cause of death for teenagers or younger children.

Police have said three adults affiliated with the Islamic Center were killed during the attack, including a security guard, who officials said played a crucial role in limiting the loss of life.

Two attackers, aged 17 and 18, also died in the shooting, apparently taking their own lives in a stolen car they used to transport them to the site of the attack.

San Diego police chief Scott Wahl said Monday that the shooting was being investigated as a hate crime and that the mother of one of the suspects had found a note.

“At this point, there was definitely hate rhetoric that was involved,” he said. “There was generalized hate rhetoric and speech,” but no specific threat was made to “any facility or any place,” he said.