At least 17 students at a Watts elementary school were sickened by an unknown substance shortly after lunch on Friday, authorities said.
Paramedics were responding to Ritter Elementary just before 12:30 p.m., according to Supervisor Bernard Peters of Los Angeles County Fire Department.
The children were experiencing nausea and upset stomach, Peters said.
A shelter-in-place order was issued at the school, according to a spokeswoman for the Los Angeles Unified School District.
Later Friday evening, the district announced it had launched an investigation into the illnesses, saying “about 20″ children were sickened. One student was transported to a hospital but others were released to their parents, the district said in a statement.
Food samples will be tested to determined if a food-borne illness caused the incident, and the LAUSD Office of Environmental Health and Safety will conduct other tests, the district stated.
Ritter Elementary is in the 11100 block of Watts Avenue (map).
KTLA’s Jennifer Thang contributed to this report.