KANSAS CITY, Mo. (AP) — More than 500 participants will paddle 340 miles in a race along the Missouri River from Kansas City to St. Louis.

The seventh annual Missouri River 340 started Tuesday and is expected to end Friday in St. Charles.

Organizers say this year's event attracted a record number of racers, despite the recent blistering heat.

Safety boats are following the paddlers, and most racers have friends and family following them with food and camping supplies.

The Missouri River 340 is supported by Missouri River Relief and Missouri American Water.