A deluge of rain in Oklahoma forced Beach Boys fans to cut a meet-and-greet short after a suspected tornado sent water pouring through a casino's roof, according to witnesses and officials. The surf rock band, as led by founding member Mike Love, had wrapped up their Riverwind Casino gig Saturday night when the storm whipped through Norman, a casino spokesperson said. The winds toppled power lines outside the casino and ripped off a chunk of its roof, prompting rain water to spill into the auditorium as concertgoers lingered for autographs with the iconic '60s group. Oklahoma Gov. Mary Fallin was among the concertgoers told to evacuate out of fear that the roof could cave in, according to KWTV-TV. "I looked up towards the balcony and there was this huge flood of rain coming through the roof," Fallin told the Oklahoma City television station. The governor tweeted a photo of herself alongside husband Wade Christensen during happier times - when Love's band was performing. Guests at the adjacent Riverwind Hotel were evacuated to nearby lodging after the building lost power, casino officials said, noting that several buildings were flooded and cars in the parking lot were damaged. The National Weather Service issued a tornado warning for much of the region, prompting students at the nearby University of Oklahoma to take shelter for at least 15 minutes as the rough weather barreled toward Texas. Oklahoma Department of Emergency Management spokeswoman Keli Cain said at least three tornadoes were reported in Caddo, Comanche and McClain counties. There were no immediate reports of injuries or deaths.