A severe storm packing hurricane-force winds pummeled Houston on Thursday, killing at least four people, blowing windows out of high-rise buildings and leaving some 800,000 homes without power as much of the city was plunged into darkness, the mayor said.

Much of downtown Houston and its commercial district were littered with fallen power lines and glass from shattered windows following the storm, with traffic and street lights knocked out across the city, the mayor, John Whitmire said in an interview on local television station KRIV.