San Diego County health officials are warning about potentially lethal flesh-eating bacteria infections contracted through black tar heroin drug use after nine people were diagnosed with severe myonecrosis.

Seven of them died from their infections.

San Diego County chief public health officer Dr. Wilma Wooten issued a warning in a statement on Wednesday that added that some users are also developing wound botulism.

"People who use black tar heroin are not only at higher risk of dying from an overdose, but also more prone to developing myonecrosis and wound botulism," said Wooten.

The San Diego Union Tribune described the horrific symptoms of a myonecrosis infection:

Symptoms of myonecrosis include severe pain in the area around a wound or injection site; swelling in the area around a wound; pale skin that quickly turns gray, dark red, purple or black; blisters with foul-smelling discharge; fever; air under the skin; excessive sweating; and increased heart rate.

A myonecrosis infection can lead to shock, amputations and even death if left untreated.

Five of the people who died were men, and the patients ranged from 19 to 57 years old.

County health officials warned the local medical community to look for symptoms of myonecrosis and wound botulism.

Here's more about the heroin crisis in San Diego: