Ten tornadoes tore through the US state of Texas overnight, killing at least six people as they levelled homes, local authorities said on Thursday. As day broke, first responders were still searching for survivors in the north of the state, in particular in the town of Granbury in Hood County, Nathan Stringer, a North Texas public information officer, said “There were an estimated 10 tornados which occurred over North Texas last night,” Stringer said in an email. “It is still unknown how many total communities were affected, however, there was a large portion of Hood County and the City of Granbury affected.” “The main concern is life safety and finding victims that still need our help,” Hood County Sheriff Roger Deeds told reporters. Overnight, medical relief spokesman Matt Zavadsky said about 100 people were injured. The Dallas Morning News ran photos of swirling dark blue masses in the sky, homes damaged by fallen trees and an 18-wheel truck tipped over onto a compact car. As the sun came up on Thursday, aerial video showed scenes of devastation, including demolished houses. Hood County is southwest of Dallas.