The U.S. military has spotted airplane wreckage in the area off northeast Jamaica where a single-engine plane from Rochester, New York, was last heard from Friday. The Jamaica Defense Force (JDF) told the Jamaica Gleaner that possible wreckage was seen in the water near Port Antonio, about 14 miles off the coast of the small island, and officials also announced that an oil slick had been found nearby.

“An oil slick indicating where the aircraft may have gone down has been spotted in the area where we suspect the crash took place,” Maj. Basil Jarrett of the JDF said at a press conference in Kingston. 

Search teams from the JDF Coast Guard, the Jamaican Marine Police and the U.S. Coast Guard were combing through the area Friday evening after the plane carrying Larry Glazer, a real estate developer, and his wife, Jane, failed to land in Naples, Florida. Ken Glazer, their son, previously told NBC that Larry and Jane were the only two occupants on board the Socata TBM-700 plane when it crashed at approximately 2:15 p.m. EDT.

At one point the pilot contacted air traffic control saying his current altitude of 28,000 feet was too high and sought permission to fly at 18,000 feet. Air traffic control said the Socata, which is capable of seating seven people, could fly at 25,000 but was told that was still too high, according to NBC.

“We need to descend,” the pilot said. “We have an indication that is not correct on the plane. …We need to get lower.”

The plane soon became “unresponsive,” inspiring U.S. authorities to deploy two F-15 fighter planes to search for the Socata. By this point the Glazers had flown hundreds of miles off course, with the witnesses saying the pilot was “unconscious and slumped over” in the cockpit.

Officials at NORAD, the joint Canadian and American air command, suggested on Twitter that the people on board may have suffered from hypoxia, or lack of oxygen, that could have rendered the pilot and passenger incapacitated. While it’s not clear to which “indication” the pilot was referring, although depressurization can occur when planes rise too high to quickly, effectively suffocating passengers.

“The Glazers were innovative and generous people who were committed to revitalizing downtown Rochester and making the city they loved a better place for all,” said New York State Governor Andrew Cuomo, as quoted by the Associated Press. “I offer my deepest condolences to the Glazers’ family and friends during this difficult and trying time.” 

Search and rescue efforts will continue through the night, Jamaican officials said at a press conference, with a U.S. vessel expected to arrive to help Saturday morning.