Mystery in the water -- -- popular vacation spot a late making hundreds of swimmers sick. ABC's -- gotten tonight in what authorities believe is the culprit. The easy beloved summer haven for failed... See More
Mystery in the water -- -- popular vacation spot a late making hundreds of swimmers sick. ABC's -- gotten tonight in what authorities believe is the culprit. The easy beloved summer haven for failed us on weekends it's packed. Yeah in it's this product but tonight horseshoe lake is closed -- Health officials are scrambling to determine what turned its placid waters into a hazard after more than. 200 swimmers got sick luckily none of -- kids at the summer camp we got a call this morning from a parent concerned parent and an email that -- -- They had heard reports about a potential problem the lake that problem still a mystery tonight at health officials have ruled out -- -- -- They don't suspect a virus like -- virus that vicious stunning but that we'll hear about on cruise ships. Horseshoe lake has had a norovirus outbreak before and out water samples are being sent to the CDC in Atlanta. We were gonna have a family reunion out here this weekend and so now I have to get a -- of and one a lot of notes can be somewhere else the question for -- us tonight. How can you tell if there's a danger in the late Stanley swings it. Experts say there are a few things you can do to protect yourself and likes like this around the country. Never go in if it's overcrowding when you get out wash your hands and never drink the water. But officials tell us what you -- should be open again for too long. Matt Gutman ABC news plan.
This transcript has been automatically generated and may not be 100% accurate.