A Delta Airlines passenger plane dumped fuel over schools near Los Angeles International Airport amidst an emergency landing Tuesday. Dozens of students were reportedly treated for skin irritation and breathing problems. The incident might have violated aviation rules, reports say, as fuel dumping in emergency landings are allowed only above designated areas and at a high altitude. Delta Airlines Boeing 777-200 flight had just taken off from Los Angeles on its way to Shanghai in China with 181 people on board Tuesday just before noon, when the pilots stopped the climb at 8000 feet reporting engine trouble, according to Aviation Herald. The aircraft returned to the airport safely, during which it performed an emergency fuel dump to reduce landing weight, Delta airlines confirmed in a statement. Out of seven schools over which jet fuel dropped, the Park Avenue Elementary School in Cudahy was the mainly affected. 31 people, including 20 children, reportedly suffered minor injuries. The Los Angeles Fire Department crew, who responded to an emergency call, said some liquid rained down onto the school playground, where two classes were being held in open air. The Federal Aviation Administration said it is thoroughly investigating the circumstances behind this incident. There are special fuel-dumping procedures for aircraft operating into and out of any major U.S. airport. "These procedures call for fuel to be dumped over designated unpopulated areas, typically at higher altitudes so the fuel atomizes and disperses before it reaches the ground," the U.S. aviation authority said in a statement.