A fuel leak discovered early Saturday morning from a gas station in Brookhaven Borough, Delaware County, has killed fish and contaminated an elementary school’s retention pond and Chester Creek.

The leaked gasoline from the Gas ‘N’ Go at the corner of Coebourn Boulevard and Edgmont Avenue flowed into a storm water system that drains into a retention pond behind Coebourn Elementary School, Brookhaven police said. The storm water system also flows into Chester Creek, which runs along and through Aston Township, Chester Township, Upland Borough, and the city of Chester.

Officials found dead fish and small amphibians in an unnamed tributary to Chester Creek in the borough. They could not confirm the number that had died beyond saying it was in the “double digits.”

Police warned residents to stay away from the watershed and to keep children and pets away from runoff. Families spent Saturday morning and early afternoon at the elementary school for a car show with music, food, and raffles to benefit the borough’s veteran banner program.

Emergency responders arrived to clean up the fuel spill around 6 a.m. Saturday, according to the Brookhaven Fire Company. Delaware County’s hazardous materials team and the Pennsylvania Department of Environmental Protection joined the fire company at the scene Saturday morning and cleanup efforts continued into the afternoon, local emergency officials said.

The Department of Environmental Protection is investigating the cause of the spill.