OBERLIN, Ohio — Authorities have confirmed that seven people were exposed to an unknown substance after officers responded to an overdose call at the Oberlin Walmart Tuesday afternoon that triggered a hazmat situation and decontamination procedures at nearby Mercy Health Allen Hospital.

"Since the initial exposure, we had five additional people for a total of seven, being treated for exposure and related symptoms," said Chief Ryan Warfield, Oberlin Police Department.

According to police sources, the hazmat situation started when officers responded to a drug overdose in the Walmart parking lot. While the officer was interacting with the person who overdosed, they were both exposed to a substance that caused them to become unresponsive. Following the incident, five health care workers were exposed.

Hazmat situation started when police were called for a suspected overdose in Walmart parking lot in Oberlin. During response ofc&suspect were exposed to substance which caused them to become unresponsive according to police. #WEWS pic.twitter.com/GKNzOVrJ3v — Tracy Carloss (@TracyCarloss) October 29, 2019

The unknown substance is now being tested at the Lorain County crime lab, police said.

The emergency room at the hospital was temporarily closed for mandatory decontamination. Crews from Lorain County Emergency Management responded and are working to sanitize the area.

On Tuesday night, Mercy Health-Allen Hospital said the emergency room was back open and released the following statement:

"The emergency department at Mercy Health – Allen Hospital has been thoroughly cleaned and sanitized after today’s situation and is no longer diverting patients. Today’s response was one that Mercy Health and our community partners prepare for regularly and the positive outcome of each patient stable and safe is the reason organizations and our Hospital develops action plans to prepare."

The Oberlin Police Department has asked the public to stay away from Walmart for the time being. Walmart is located at 46440 Highway 20.

Breaking: Hazmat situation in Lorain County. Sources tell me it happened at a Walmart and those exposed are being brought to Allen Hospital to be decontaminated. #WEWS pic.twitter.com/IofRf51PeW — Tracy Carloss (@TracyCarloss) October 29, 2019

Authorities have not released any additional information.