A wall of dust enveloped the Phoenix metro area, turning daylight into darkness for more than an hour Monday, as a monsoon storm packing thunder and lightning, high winds and sheets of rain grounded flights and damaged property. Officials at Phoenix Sky Harbor International Airport said about 125 flights were being delayed until the storm passed. Salt River Project reported an estimated 30,000 of its customers were without electricity in Apache Junction and Mesa due to the storm, the second monsoon in two days to hit the Phoenix area. It was unclear when electricity would be restored because of broken power poles, according to SRP spokesman Jeff Lane. High winds blew off part of the roof of a Phoenix apartment onto the tops of some cars parked outside. One person in a car was treated for minor injuries, city firefighters said, and 20 residents were displaced. In Mesa, firefighters said a tree fell onto a home and briefly trapped a 70-year-old man who was taken to a hospital in stable condition. The storm moved from east to west through the region, dropping nearly an inch of rain in some spots and hail on some highways. There were no immediate reports of any traffic accidents, however. A monsoon late Sunday knocked out power lines in Buckeye, affecting about 21,000 residents who get their electricity from Arizona Public Service. According to the National Weather Service, 50 miles per hour (80 kilometers per hour) winds created dust storms throughout the Buckeye area about 36 miles (58 kilometers) west of Phoenix. Power was restored to almost all of the affected Buckeye residents by Monday afternoon before the second storm hit. Dust storms are common during Arizona's monsoon season that runs from mid-June to the end of September.