An eight-year-old boy who was flown to the U.S. in order to have a massive tumor removed from his face, died after suffering a reaction to anesthesia used during the surgery, TMZ reports. The boy, Matadi Sela, was brought to the U.S. by the foundation of former NBA player Dikembe Mutombo. The foundation announced on Saturday that Petit died after he “suffered a rare and unpredictable genetic reaction to anesthesia.” Petit was born in the Democratic Republic of Congo, with a cleft lip and a facial tumor, the foundation said. “We are devastated by the loss of Matadi and our heart goes out to his father, his mother and the rest of his family, and all his old and new friends,” the foundation said. The Mutombo foundation is dedicated to improving the health, education, and quality of life of people in Democratic Republic of Congo, Mutombo's native country.