Two people were killed Saturday when a glider crashed near a desert airport outside San Diego, firefighters said. The crash occurred at the Jacumba Airport where witnesses said the aircraft nose-dived into the ground near the gravel airport, Cal Fire Capt. Mike Mohler told U-T San Diego. The cause of the crash remained under investigation Sunday by the National Transportation Safety Board. The names of the two victims were not yet released. The U-T said Jacumba is a popular base for glider pilots who take advantage of the many thermal wind currents in the area. The temperature at the time of the crash was about 107 with winds only around 10 miles per hour.