The "cave" is actually an underground drainage system which runs from Old High to the Country Club.
Chief Holzer said the children were swept underground by the water.
A short time later, one boy crawled out of a curbside drain.
His sister re-surfaced a few hundred yards downstream in the Martin Plaza area.
Rescue crews were searching that area looking for a 13-year-old boy.
That's when Holzer said police located him near the area where the incident started.
"It's just one of those things where we're thanking our lucky stars it's not a recovery, and it ended well," said Chief Holzer.
Authorities said the 13-year-old was taken to United Regional for treatment of possible hypothermia and shock, but he and the other children appear to be okay.
Copyright 2016 Nexstar Broadcasting, Inc. All rights reserved. This material may not be published, broadcast, rewritten, or redistributed.