Ft. Collins, CO – A wildfire in northern Colorado has destroyed a house and a garage, burning 5,600 acres. The fire threatens at least 23 other homes and has forced scores of families to flee. It defied expectations Thursday night by jumping from treetop to treetop. Officials say fires usually lay down at night as winds calm, but that hasn't happened with this fire in Poudre Canyon, northwest of Fort Collins. Gray smoke billowing thousands of feet into the sky grounded air tankers Thursday afternoon. The fire was 15 percent contained last night. The Picnic Rock fire began Tuesday when a yard fire got out of control.