PHILADELPHIA (CBS) — The official cause of death has been released for a first-grader who died after suffering a medical condition at a school in Philadelphia earlier this week.

According to investigators, the seven-year-old had a heart anomaly, a birth defect, which caused his death.

The boy, who attended Andrew Jackson Elementary School, collapsed at about 2 p.m. Wednesday inside the school and later died at Children’s Hospital of Philadelphia. (See Related Story)

While a retired nurse and two other staff members administered CPR to the boy, parents are outraged that a full-time nurse is not employed at the school due to budget cuts.

The school only has a part-time nurse on Thursdays and every other Friday.

While officials aren’t sure if a nurse would have made a difference, parents at the school say they shouldn’t have to take that chance.

Those parents rallied outside the school Thursday, demanding changes, including schools not opening in September if there isn’t a full-time nurse in each and every building.

“We have a right as parents and our children have a right as students to a school nurse at all times,” President of Friends of Jackson Melissa Wilde said.

The district spokesperson tells CBS3 that only some schools in Philadelphia have a full-time nurse because of budget cuts.

Philadelphia School District Superintendent William Hite released a statement following the tragedy that read in part:

This incident, however, illustrates the serious needs and challenges that our students, teachers, staff and principals face every day. During times of tragedy, our community should not have to question whether an extra staff member or program would have made a difference. We should all feel confident that our schools have everything they need.

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