A semi-truck fire caused a mess and a long backup on westbound Interstate-40 Saturday night and Sunday. DPS says the truck’s trailer caught fire at around 8:30 p.m. just past the Fourth Street Bridge in Flagstaff. The trailer contained yogurt, so clean up has taken time. The fire burned for quite a while before it was extinguished. No one was hurt. The incident was cleared at around 5 p.m. Sunday.