Already dealing with soaring prices, contaminated gasoline from a supplier in Anacortes was sold to customers at the Safeway gas station in Maple Valley last Sunday, causing mechanical problems for their vehicles.

Gas mixed with water was pumped into at least 10 vehicles before the problem was corrected, according to Safeway spokeswoman Cherie Myers. Water can cause a car to stall because it is heavier than gas.

The problem was first reported at about 5 p.m., when two customers’ cars wouldn’t start, Myers said. Using remote monitoring equipment, fuel suppliers detected the bad gas in underground tanks and the station was closed. It reopened briefly at 7:30, but faulty fuel was again found in the underground tanks, causing the station to close again until 10:30. After that, sales of gas were reinstated with no further difficulties, Myers said.

Shell supplied the contaminated gas, reportedly from its refinery in Anacortes. Myers said Shell will reimburse customers for any obad fuel they purchased and for related costs, such as renting cars when their own vehicles wouldn’t run.

A second Safeway gas station, this one at the grocery outlet in Des Moines, was scheduled to receive gas from the same supplier. The delivery was stopped, however, and no problems for customers there were reported, Myers said.

Statewide, gas prices reached a record per-gallon pump price of $4 or more last weekend.