How did the towns people find drowned bodies in the water adventures of tom sawyer?

All of St. Petersburg's citizens believed Tom Sawyer, Joe Harper, and Huck Finn had drowned. They attempted to find the bodies but couldn't, as the boys were safe and sound on Jackson's Island the whole time. Later, there was a funeral, which the boys attended. It was unknown to the townspeople until the three boys walked into the middle of the sermon.