State health authorities in West Virginia are investigating several cases of the hepatitis C virus (HCV) that may be linked to a heart clinic in Raleigh county that may have exposed patients to blood-borne illnesses through injectable medications they received there, the Register-Herald reports.

According to a letter sent out earlier this month by the West Virginia Department of Health and Human Resources, any patients who received a cardiac stress test at the Raleigh Hearth Clinic in the town of Beckley between March 1, 2012 and March 27, 2015 should be tested for hepatitis C, hepatitis B virus (HBV) and HIV.

So far, authorities say it is still unclear how exactly transmissions could have occurred at the facility, but have assured patients that it was not due to improper practices at the clinic. Free testing for all three diseases is available at the Raleigh Heart Clinic for those affected.

In the meantime, the Office of Infectious Diseases at the U.S. Centers for Disease Control and Prevention, the Bureau for Public Health’s Office of Epidemiology and Prevention Services and the Beckley-Raleigh County Health Department are helping out with an official investigation to determine exactly what led to the potential exposures.