The pilots of a Delta flight conducting an emergency landing didn’t tell air traffic controllers before dumping fuel that wound up falling on several Los Angeles area schools on Tuesday, aviation officials said Thursday.

“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 Federal Aviation Administration (FAA) said in a statement emailed to TIME.

Pilots typically notify flight controllers if they believe they need to dump fuel, a procedure that is sometimes done to reduce an aircraft’s weight ahead of an emergency landing for safety reasons.

According to a recording of the conversation between a Flight 89 pilot and an air traffic controller from LiveATC.net and reported by CNN, a pilot explicitly said he or she did not need to dump fuel:

Tower: “OK, so you don’t need to hold or dump fuel or anything like that?” Pilot: “Uh, negative.“

Furthermore, the pilots did not dump fuel “at an optimal altitude” that would have allowed the fuel to dissipate before it reached the ground, the FAA said.

If circumstances allow, controllers can direct pilots in need of a fuel dump to an area where it’s safer to perform the maneuver. However, in an emergency situation, it is ultimately up to pilots to do what they believe is necessary for the safety of their aircraft and those aboard. Whether the fuel dump in Tuesday’s situation was warranted given the aircraft’s situation and position will be central to the investigation of the incident.

Delta Air Lines refused to comment, citing the ongoing investigation. A Delta spokesperson previously said that the aircraft “landed safely after a release of fuel, which was required as part of normal procedure to reach a safe landing weight.”

Delta Air Lines Flight 89 had been en route from Los Angeles to Shanghai and landed just 15 minutes after takeoff on Tuesday at 11:47 a.m., Los Angeles International Airport officials had said.

Fuel dumped by the aircraft fell across five elementary schools and one high school and fire crews treated 60 people for minor injuries, officials said, according to CNN.

No one was hospitalized as a result of the incident. “Students and staff were on the playground at the time and may have been sprayed by fuel or inhaled fumes,” a Los Angeles Unified School District spokesperson said in an earlier statement.

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Write to Sanya Mansoor at sanya.mansoor@time.com.