State officials are investigating the source of a petroleum spill on the Green River in the Seattle suburb of Kent. The Puget Sound Regional Fire Authority Capt. Kyle Ohashi says a tip led to a hazardous materials response to the river Tuesday afternoon for a spill that started in Kent and floated to Tukwila. Ohashi says firefighters could see a sheen on the river’s surface and set two sets of absorbent booms across the river to stop the material’s movement. Firefighters and a King County Sheriff’s Office helicopter were unable to find the source of the spill. The state Department of Ecology will continue to determine the source of the spill and what caused it.