LOS ANGELES – Coroners in four counties say as many as 25 people may have died of heat- related causes during an eight-day siege that began to ebb Wednesday. L.A. County coroner’s Lt. Larry Dietz said his office was investigating 15 possible heat-related deaths, the youngest victim a 26-year-old who became separated from his friends while dirt biking Saturday. Deputy Coroner Henry Proo said seven deaths in typically hot Imperial County were considered heat-related. There were also two in San Bernardino County and one in Riverside County. Among the dead was Michael Visser, a dirt biker found in northern Los Angeles County. Utility crews struggled Wednesday to restore electricity to tens of thousands of homes left without power after increased air conditioner use strained power grids. Southern California Edison on Wednesday reported outages affecting 20,500 customers primarily in Long Beach, Irvine, Corona, Ontario, Whittier and Norwalk – nearly 9,000 of whom have been without power for more than a day. Meanwhile, nearly 9,000 Los Angeles customers were without service, Department of Water and Power spokeswoman Gale Harris said. 160Want local news?Sign up for the Localist and stay informed Something went wrong. Please try again.subscribeCongratulations! You’re all set! In Imperial County, authorities also are blaming 116-degree temperatures for the deaths of an elderly woman found dead last week in her home that didn’t have air conditioning and a 58-year-old man discovered by friends in his trailer, which had no electricity or running water. Proo said authorities also discovered last week and Monday the bodies of illegal immigrants who died in the heat after crossing the border. One, a woman, was 37. The other, a man, was 27. “A healthy adult cannot carry enough water to safely make it across the desert,” Proo said. “I’ve been saying it for years, and I’ve proved it every time I go out on one of these calls.” Temperatures were expected to drop as much as 20 degrees in most parts of Southern California. During the heat wave, temperatures often soared past 110 degrees and nighttime temperatures fell only a few degrees.