Investigators are still trying to determine what caused a two-alarm fire that damaged several businesses in downtown Las Vegas. The blaze broke out just after 2:00 this morning at the corner of Las Vegas Boulevard and Bonneville Avenue. Four businesses, including two bail bonds operations, a law office and a sandwich shop, were damaged in the fire. No injuries were reported. Initial reports say the roof caved in before the fire was put out just after 3:00 a.m. Damage estimates have not yet been released.