At about 2320 Pacific time, a Cessna 310L landed gear up on runway 30L at North Las Vegas Airport. None of the five aboard was injured. The pilot told investigators he was distracted from his pre-landing checklist by looking for traffic and forgot to extend the landing gear. He did not notice the green gear-down indicators were not illuminated and the gear warning horn did not activate until about a second before the propellers struck the runway. The control tower was closed, and air traffic controllers at another airport were notified that the airplane was disabled on the runway. No flight service station was notified and no notam was issued. At about 0545 the next morning a departing airplane reported a near miss with the disabled airplane.