Petroleum products were detected in the Red Hill well that was pumping drinking water to hundreds of military families that reported tainted water this week, Navy officials said Thursday.

Water samples from the well were sent to a mainland lab earlier this week and detected the presence of petroleum, Rear Adm. Blake Converse said during a Facebook Live.

From well samples taken on Sunday night, officials identified trace amounts of “very volatile hydrocarbons,” which are associated with JP-5 jet fuel or diesel fuel, Converse said. A second test completed on Thursday found “clear indications of petroleum products” just above the water line in the well, he said.

“With both of these, we have pretty conclusive indications that there are volatile petroleum products in the well,” he said.

Converse, the deputy commander of the U.S. Pacific Fleet, did not detail the amount of petroleum nor where it may have come from. Testing done throughout the rest of the water distribution system yielded negative results for contaminants, he said. But he didn’t say which areas were tested. A copy of the test results was released late on Thursday.

The Navy stopped pumping from the Red Hill shaft on Sunday amid complaints that the water smelled like fuel. Many families, including children, were complaining of rashes, aches and vomiting, among other symptoms. Earlier this week, the 93,000 people on the Navy’s water system were advised by the Hawaii Department of Health to stop drinking the water and only use it for other purposes if it doesn’t smell.

On Thursday evening, DOH published a statement saying it had just received the Navy’s test results and it stood by its recommendations on water usage. The Navy’s results corroborate state test results released on Wednesday that found petroleum in a water sample from Red Hill Elementary School.

“Now that the source has been identified and isolated, we are developing a plan to restore the potable water system to EPA standards, identify how this contaminant got in the well, and fix the well,” Converse said.

“Based on the findings, we will work with the Department of Health to revise the public health guidance and develop the way ahead so our families and other impacted people can return to a normal life with safe, reliable water,” he added.

On Thursday evening, U.S. Rep. Kai Kahele tweeted water testing results he said the Navy had shared with the congressional delegation. He wrote that the contaminants in the water were xylene, naphthalene and total petroleum hydrocarbons with gasoline components.

Xylene is a flammable liquid with a sweet odor that is used in petroleum products, according to the Centers for Disease Control and Prevention. Exposure to the chemical can also cause headaches, dizziness, confusion and loss of muscle coordination, the CDC says on its website.

Naphthalene is a type of hydrocarbon. Exposure by inhalation or ingestion can cause eye irritation, headache, discomfort and nausea, among other symptoms, according to the CDC. And total petroleum hydrocarbons, or TPHs, are “a large family of several hundred chemical compounds that originally come from crude oil,” the CDC says.

All the contaminants were detected at levels that fall below DOH thresholds for drinking water safety, according to the information Kahele shared.

However, the Navy has received complaints from 680 military households, officials said, and many of them have reported being sickened after drinking the water, bathing in it or even just breathing fumes.

The Navy has urged affected households to flush the system by running their water for three to five minutes a day.

Meanwhile, the Honolulu Board of Water Supply, whose Halawa shaft provides water to 400,000 people from Moanalua to Hawaii Kai, is bracing for impact. In anticipation of the Red Hill contamination possibly migrating across the Halawa valley toward the Halawa shaft, BWS has slowed pumping from that source by half.

The Navy has established a medical hotline for residents to report health problems. That number is (808) 433-8102.