NEW YORK (Reuters) -BP was responding to a release of refined products on the Olympic Pipeline System east of Everett, Washington, and had partially restored part of the system, the company said on Monday.

The BP-operated Olympic shut its pipelines in the area after the discharge on Sunday. The system consists of two pipelines in the area.

The segment of the pipeline system unimpacted by the issue was restored on Sunday, resuming product delivery on that line, the company said. 

The incident is still under investigation, BP said.

Olympic Pipeline is a 400-mile pipeline system moving fuels from northern Washington to Oregon. The pipeline transports key refined petroleum products including gasoline and diesel and supplies jet fuel to Seattle-Tacoma International Airport (Sea-Tac).

Operations at Sea-Tac were not impacted by the incident and the airport had plenty of stored fuel on hand to manage the situation, a Sea-Tac spokesperson said.