Last week, an emergency room in the Pacific Northwest was briefly quarantined after five people experienced mysterious hallucinations from an unidentified illness believed to be spread by touch, according to news reports. The Coos County, Oregon, Sheriff’s Office said the illness appears to be spreading by contact.

Those affected included two sheriff’s deputies and a hospital worker. According to Oregon Live, the incident started early Wednesday, Oct. 12, when a 54-year-old caregiver in North Bend, Oregon, called the Coos Bay Sheriff’s Office to report that seven to eight people were “trying to take the roof off her vehicle.” Deputies who responded to the call said they found nothing, but after the caregiver reported the unseen vandals a second time, she was escorted to a nearby hospital for suspected hallucinations.

Shortly afterward, one of the deputies who responded to the call began experiencing symptoms described as “similar” by KVAL News and returned to the hospital. Soon after that, the other deputy, a hospital worker and the caregiver’s 78-year-old patient also began hallucinating and were hospitalized, KVAL reported.

A hazmat team was deployed to both the hospital and the initial residence, clearing the emergency room and providing a protocol to the sheriff’s office to decontaminate vehicles and equipment. The team was unable to locate a common source of contamination. Blood tests also failed to find anything unusual.

According to police spokesperson Patrick Downing, initial investigations suggested the 78-year-old patient’s narcotic fentanyl patches could be the source of the hallucinations, but that explanation was later ruled out, KVAL News reported.

“Investigation has found that all those patches and potential medications that may have caused the symptoms have been accounted for,” Downing told KVAL. “The vehicles, equipment, and uniforms have been checked, with no contaminates identified or located on or about them.”

Authorities say the investigation is ongoing.