(CNN) -- After revelers celebrated the Fourth of July at a Michigan lake, some started testing positive for Covid-19 -- prompting health officials to warn other party-goers that they might have be infected, too.
The Health Department of Northwest Michigan said other health officials in the state reported that several people have tested positive "after attending the festivities at the Torch Lake sandbar over the Fourth of July holiday," the department said Friday.
Those who tested positive weren't able to identify everyone they had contact with, "and therefore we want to make the public aware that those who attended could be at risk for exposure, and additional cases could be seen in the coming days," the health department said.
"If you were at the Torch Lake Sandbar party over 4th of July weekend, you should monitor for signs and symptoms of COVID-19 and seek testing if symptoms should develop or if you were at high risk for exposure due to being in close proximity with others or not wearing a cloth facial covering."
The disease can be mild to severe, and some infected carriers have no symptoms at all when they infect others.
Those who do get symptoms typically get sick two to 14 days after exposure to the virus, and symptoms can include shortness of breath, fever, cough, the loss of taste and smell, and diarrhea.
"Anyone that is self-monitoring as a result of a potential exposure to COVID-19 should keep away from others as much as possible and limit travel," the health department said.
"If you are self-monitoring and develop symptoms, you should call your primary care physician first for testing. If you do not have a primary care physician, please call the Health Department of Northwest Michigan at 1-800-432-4121."