A small plane that crashed Friday after striking a pickup truck on the runway was carrying two University of Maine students and one alumnus, who all died in the crash, the school said Saturday. The victims were identified as David Cheney, 22, of Beverly, Mass.; Marcelo Rugini, 24, an exchange student from Brazil; and William ‘‘B.J.’’ Hannigan III, 24, of South Portland. All were members of the Lambda Chi Alpha fraternity. The Cessna 172 was on a Knox County Regional Airport runway Friday night when it struck the truck, which was authorized to be on airport grounds, Knox County Chief Deputy Sheriff Tim Carroll said. The plane continued to climb and as it turned, dived into the woods, and burst into flames, the sheriff’s office said.