A terrifying shooting spree on a 50-mile stretch of Texas highways left two motorcyclists dead and two others injured on Friday, authorities say. The attack began on a feeder road to Interstate 45 in the Houston suburb of Spring, where a biker was shot but survived. Cops say the shooter continued onto the freeway and eventually onto nearby Highway 19, where they gunned down three more motorcyclists as they rode near Huntsville—an hour north of Spring. The suspected shooter’s motive remains unknown, and cops say the gunman is still on the loose—prompting officers to shut down the southbound lanes of a portion of Interstate 45 completely. The condition of the two surviving motorcyclists wasn’t immediately released.