08-30-2007CAMERON PARK, CaAuthorities said California's heat wave might have contributed to the crashes of two small planes within hours of each other as they were taking off from the same airport.Two people were killed and two others critically injured in the second crash Thursday in Cameron Park, in the Sierra foothills east of Sacramento. In the earlier crash, two people sustained moderate injuries.The warmer air might not have provided enough lift for the planes, said Bob Petersen, air squadron commander for the El Dorado County Sheriff's Department."As temperature goes up, the air gets thinner," he said.Authorities said thetwo crashes were not connected and both remain under investigation."It's just a strange coincidence," sheriff's spokesman Lt. Kevin House said. "We never had two crashes in the same day."Killed in the second crash were Patricia French, 60, and Robert French, 62, who died at the scene.He also said he did not know the identities of the two people injured in the crash, nor the extent of their injuries.Their Beechcraft went down 200 yards from the runway about 12:35 p.m. Thursday. They had been headed for Ensenada, Mexico.