Downed power lines caused traffic to back up on Highway 99 in Chico this morning. The south bound lanes of Highway 99 were reopened after 8 am this after the lines fell after 7:30. The CHP closed the lanes due to a fire caused by the downed lines. Chico Police dispatch reported that traffic was backed up all the way to Bruce Road. PG&E arrived and worked on killing the downed power lines.