It is hard to hold a video game trade show during a power failure, as attendees of the Electronic Entertainment Expo learned the hard way on Wednesday, just as the show was getting underway. The power went out to mainly the media and administrative facilities at the Los Angeles Convention Center, though it was available on the show floor where games publishers, developers and hardware makers had set up their booths, said Carolyn Rauch, vice president of the Entertainment Software Association, Reuters reported. "The power outage stemmed from a problem with the city's power grid. We're working with them to rectify it as soon as possible," Rauch said. The Los Angeles Department of Water and Power said the cause was still undetermined, but about 10 percent of the show facilities had no power at late morning. A crew was delivering a backup transformer to the Convention Center, which was expected to have full electricity back by 4 p.m. PDT (2300 GMT). The E3 gathering is the gaming industry's top deal-making and media event, with thousands of participants congregating each year in Los Angeles to learn about the latest and greatest in gaming. This year, the top gaming console makers, Microsoft Corp. -- Sony Corp., and Nintendo Co. Ltd.. -- unveiled their latest-generation consoles. Vendors said they were struggling because of the partial outage. "We can't do any of the lighting or music effects, we can't demonstrate any of our products," said Dirk Foster, director of marketing for video game accessory maker Pelican, who added that his company had planned to conduct demos in some of the meeting rooms off the show floor.