A Delta Air Lines flight crew that dumped fuel on several Los Angeles area schools before making an emergency landing, causing minor injuries to schoolchildren, did not inform air traffic controllers it planned to do so, the Federal Aviation Administration (FAA) said Wednesday.

Delta Flight 89, which was turned back for an emergency landing at Los Angeles International Airport after departing for Shanghai, dumped fuel on the playgrounds of at least four elementary schools in its flight path, causing minor injuries to at least 44 children and adults on the ground, the Los Angeles County Fire Department said on Twitter.

None of the children or adults needed hospitalization, the department added.

"A review of yesterday's air traffic control communications shows the Delta Flight 89 crew did not tell air traffic control that they needed to dump fuel," the FAA said. "In this emergency situation, the fuel-dumping procedure did not occur at an optimal altitude that would have allowed the fuel to atomize properly."

Before making emergency landings, planes often dump fuel to reduce their weight for safety reasons. The FAA said in a statement that air crews will typically notify air traffic control of an emergency and indicate the need to dump fuel, with controllers then directing the crew to an appropriate fuel-dumping area. The agency said it is continuing to investigate the circumstances behind the incident.

The Los Angeles Times obtained audio of the conversation, quoting a controller asking the Delta pilot about fuel.

"OK, so you don't need to hold to dump fuel or anything like that?" the control asked. The pilot responded, "Negative."

Delta said on Tuesday it shares "concerns regarding reported minor injuries to adults and children at a school in the area" and said the fuel was dumped to reach a safe landing weight.

Delta declined to comment Wednesday on the FAA statement but said on its website that 13 airline cleaning crews worked with school crews "to clean all outside surfaces that students could come into contact with." The schools all reopened as scheduled on Wednesday.