Officials in the Los Angeles area are investigating after an aircraft apparently dumped jet fuel Tuesday afternoon on a playground while en route to Los Angeles International Airport, leaving several people with minor injuries.

Los Angeles County Fire Department officials said they responded to an elementary school shortly after noon Pacific time in the 8000 block of Park Avenue in Cudahy after the aircraft apparently dumped the fuel while on a final approach to the airport.

Twenty children and 11 adults complained of minor injuries, officials said. No one was taken to a hospital, officials said, and no evacuations were initiated.

Fire officials say they also treated more than two dozen patients at other schools, all with injuries that were not life-threatening.

In a statement, Federal Aviation Administration spokesman Allen Kenitzer said Delta Air Lines Flight 89 declared an emergency after departing from the airport, then returned to the airport and “landed without incident.”

“The FAA is aware of and looking into reports that children at a school east of LAX are being treated for fuel exposure,” the statement said.

According to the FAA, fuel-dumping procedures for aircraft traveling to or from any major U.S. airport call for fuel to be dumped over designated unpopulated areas, usually at higher altitudes where fuel can disperse before it reaches the ground.

Delta spokesman Adrian Gee said in a statement the flight “experienced an engine issue requiring the aircraft to return quickly to LAX. The aircraft landed safely after a release of fuel, which was required as part of normal procedure to reach a safe landing weight. We are in touch with Los Angeles World Airports and the LA County Fire Department and share concerns regarding reported minor injuries to adults and children at a school in the area."

Airport spokesman Heath Montgomery said the flight, headed to Shanghai, departed about 11:30 a.m. local time before the pilot declared an emergency related to a mechanical issue shortly after takeoff. The plane, a Boeing 777-200, then returned to the airport safely and returned to the gate under its own power.

Officials said 70 emergency personnel were at the scene. A person who answered the phone at Park Avenue Elementary in Cudahy said officials are continuing to investigate. KABC reported that children suffered from skin irritation.

The location is about 15 miles east of Los Angeles International Airport.