HONOLULU (AP) — The Hawaii State Department of Health said Wednesday a laboratory has detected petroleum product in a water sample from an elementary school near Pearl Harbor amid heightened concerns that fuel from a massive Navy storage facility could contaminate Oahu’s water supply.

The department said the test result from a University of Hawaii lab is preliminary, and it’s not yet clear what type of petroleum was in the water. The sample was taken Tuesday at Red Hill Elementary School. The department is still awaiting test results of samples sent to a lab in California.

For three days, hundreds of residents in Navy housing have complained of a fuel-like odor coming from their tap water. Some have said they suffered from stomach pain and headaches.

The department said all complaints have come from people using the Navy’s water system, and not from anyone who gets their water from Honolulu’s municipal water utility. Both the Navy and the utility have wells that draw on the Moanalua-Waimalu aquifer which is located 100 feet underneath the Navy’s fuel storage tanks at Red Hill.

The Navy on Sunday shut down a Red Hill well that draws water from the aquifer out of an “abundance of caution,” a spokesperson said.

The department has advised all those using the Navy’s water not to drink their tap water. It’s recommending that those who can smell fuel in their water not to use it for bathing, washing dishes or laundry. The system provides water to about 93,000 people living in and near Pearl Harbor.

The Navy and the state Department of Health are both investigating where the contamination is coming from, though the Navy said it has not detected any fuel in the water. The elementary school gets its water from the Navy’s water system.

Dr. Diana Felton, Hawaii’s state toxicologist, said people who ingest petroleum may experience nausea, vomiting and diarrhea as well as dizziness and headaches. Skin exposure may lead to itching and rashes. People who stop drinking effected water should start to feel better in a few hours, she said.

Felton said she won’t know whether anyone would be expected to suffer any long-term effects of drinking the water until she learns what type of petroleum was involved, but at this point she believes it’s unlikely.

Last week, the Navy said a water and fuel mixture leaked from a fire suppression system drain line into a lower tunnel in the Red Hill fuel tank farm. The Navy said no fuel leaked into the environment in that episode.

The Sierra Club of Hawaii, which is locked in legal actions with the Navy and the state over the Red Hill fuel storage, explained to NewsNation affiliate KHON a link cannot be ruled out at this point.

“Red Hill is pretty much like on the border,” explained Wayne Tanaka of the Sierra Club of Hawaii, pointing out aquifers on the map. “Halawa is a little bit more mauka as is Waiawa. The Halawa shaft is what serves all the residences, businesses, hospitals in this entire area from Halawa to Moanalua all the way to Hawaii Kai.”

KHON2 asked: Could a leak at those large Red Hill fuel tanks somehow get to the Halawa aquifer or tanks of water?

“That is a huge concern,” Tanaka said. “That is a reason why we’ve been locked horns with the Navy for the last several years. I’m just trying to get them to acknowledge the risk — existential risks — that this fuel facility poses to our drinking water supply. It’s still unclear how and where fuel flow, if there is a massive leak, how quickly and whether it will actually migrate toward the Halawa shaft, which again would be pretty catastrophic.”

“We all want to make sure that this doesn’t become a harbinger of things to come of what may be impacting a much, much, much broader segment of the population here,” Tanaka added.

Honolulu Civil Beat reported last month that officials waited months to report a January fuel leak at Pearl Harbor to the state Department of Health because they were worried doing so would hurt their ability to get a permit for the Red Hill tanks. Hawaii’s congressional delegation has asked the Department of Defense to investigate.

The tank farm contains 20 large underground fuel tanks that date back to World War II. The Navy built the tanks in two rows of 10 inside a mountain ridge 3 miles inland from Pearl Harbor. Each tank is as tall as a 25-story building.

Total storage capacity of the facility is 250 million gallons, giving the U.S. military what it calls a vital fuel reserve in the Pacific. The tanks provide the last fully U.S.-owned fuel stop for forces going from the West Coast and Hawaii to Asia and the Middle East.