Many who knew Jonathan Martinez remembered him for an infectious smile that belied a difficult life.
The 8-year-old was born with Williams syndrome, a rare genetic condition that can result in learning difficulties and medical problems such as heart and kidney ailments. He had undergone heart surgery.
Seeing Jonathan overcome these challenges makes his sudden, violent death inside his special education classroom in San Bernardino all the more difficult to bear, friends say.
Diane Abrams, who worked in the special needs class where Jonathan was a student, said she remembers him as "full of life."
"He was so special to teach…. He was curious to learn and wanted to do his very best. He was such a loving little guy. He'd sit with his hands folded at his desk and look at me and say, 'Ms. Abrams, am I being an all-star?' " she recalled.
Jonathan's week began the way it does for most children: He was dropped off at school in the morning after having spent the weekend playing with friends and family, according to neighbors.
But when a gunman walked into the boy's classroom at North Park Elementary School in San Bernardino on Monday morning, the situation took a turn for the worse.
About 10:27 a.m., the gunman fired 10 shots from a Smith & Wesson revolver. One of the bullets fatally struck the boy as he stood near his teacher, Karen Smith, who was also shot dead.
The gunman was Smith's estranged husband, Cedric Anderson. An employee at the school saw Anderson and recognized him as Smith's husband. Following normal protocol, she asked him to sign in and allowed him to walk unescorted to Smith's classroom. Once inside, he began shooting, stopping once to reload, and then shot himself.
Jonathan was airlifted to a nearby hospital but died before entering surgery. A 9-year-old boy identified as Nolan Brandy was also shot and is in stable condition.
Classmates were stunned by what happened.
Jeffrey Imbriani, 7, told the Associated Press he was still trying to process the death of his friend and soccer buddy.
"I know him because one day he just walked up to me and said, 'Can we be friends?' and I said, 'Yeah,' and we've been friends ever since," he said. "I will think of him as a very best friend."
Grief counselors met with the boy's parents and family members Tuesday morning. Throughout the day, their frontyard was lined with cars as friends and neighbors came to give their condolences.
People who have Williams syndrome often endure medical and cognitive setbacks, but the disorder can also inspire empathy in those who suffer from it. Many people with Williams syndrome, particularly young children, are known for their friendliness, said Terry Monkaba, executive director of the Williams Syndrome Assn.
"Everyone who smiles at them is their friend," Monkaba said. "They tend to notice the little things that make you feel good, like a new dress. They are often considered the mayor of their elementary school."
Some scientists believe the friendliness of those with Williams syndrome is used as a coping mechanism to diminish their anxieties.
The disorder is caused by missing genes, including one that plays a role in forming the protein elastin, leading to cell overgrowth and problems around arteries and vessels.
People with Williams syndrome can have mild to severe learning disabilities, but children with the disorder are not usually in special education programs, Monkaba said.
"Today, more and more children with Williams are included in regular classrooms with some accommodations," she said.
About 25,000 people nationwide have the disorder.
Monkaba said even though she didn't know Jonathan personally, his death is something that people in that community feel personally.
Jonathan's death, "because it was so senseless and so tragic, it just makes it that much harder," she said.
Jonathan's cousin set up a GoFundMe page to help the family cover funeral costs and has raised more than $117,000 in one day.
Mary Wilson, who lived across the street from the boy's family, described him as a well-behaved and beloved kid.
"He never left the frontyard when he played outside," she said.
Bobby and Janet Lopez walked hand in hand to the Martinez family household Tuesday afternoon with a white bouquet of flowers. They have lived in the neighborhood for 50 years and have been neighbors of the Martinez family for more than 10.
Trying to hide his tears, Bobby Lopez said he wanted to show his neighbor support.
"We could feel their pain and we know we can't take it away, but we are here to share our love," he said.
Times staff writers Matt Hamilton, Sonali Kholi and Laura Nelson contributed to this story.
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