The Los Angeles County Fire Department said firefighters assessed 17 children and nine adults who complained of minor injuries and none needed to be taken to a hospital.
The fire department said the substance sickening the students and adults was confirmed to be jet fuel.
The other schools affected were San Gabriel Elementary, Graham Elementary, Tweedy Elementary, 93rd Street Elementary and Jordan High School.More news: Auto industry cautious as China starts 2020 with 2% sales decline forecast
Up to 23 people were injured when a plane dumped fuel over a school in Los Angeles.
The flight tracking website FlightAware shows that Delta Air Lines Flight 89 to Shanghai, China, departed LAX and circled back over Southern California and returned to the airport on Tuesday.
"The aircraft landed safely after an emergency fuel release to reduce landing weight", the statement said. The school is about 19 miles east of the airport. Substance was confirmed JET FUEL'.More news: Bigg Boss 13: Is Shehnaaz Gill in love with Sidharth Shukla?
A Federal Aviation Administration spokesman did not have any immediate information.
The FAA said it was "thoroughly investigating" the incident. "There are special fuel-dumping procedures for aircraft operating into and out of any major United States airport", an FAA spokesperson wrote.
Being exposed to jet fuel will likely cause a person to experience irritant contact dermatitis, according to DermNet NZ.
All the fuel evaporated very quickly and nothing flammable remained in the air or on the ground, he said.More news: Billie Eilish to record new 'James Bond' film theme
When the plane was over the school area, the plane was at around 2,300 feet and was on final approach to the airport, a Delta spokesperson said. Compresses, creams, and ointments also can help promote healing, according to the site.