Encinitas Union School District (EUSD) sent a note out to families Sunday saying an individual at Olivenhain Pioneer Elementary has tested presumptive positive for COVID-19.
The district said the individual was in home isolation and being monitored by the Health and Human Services Agency (HHSA).
ESUD said they were notifying individuals who may have been exposed and asked them to self-quarantine.
"We have all been preparing and working to slow the spread of the COVID-19 and it is unsettling to have this happening in our community and our schools. With our schools continuing to be closed over the next few weeks, we are hopeful having students and families at home will reduce illness," the district said.
It is the first known case at a San Diego County public school district.
No other information about the individual was available.
On Monday, schools across the county will remain closed in wake of the novel coronavirus pandemic after following guidance by local health officials.
Any student age 2 to 18 can go to any school site providing meals and receive food during this period of school closures, the San Diego County Office of Education said.
For the latest information, head to NBC 7's "What to Know" article.