CHICAGO (AFP) - Authorities in the US state of Kansas on Monday (Aug 9) were investigating the death of a 10-year-old boy on what is billed as the world's tallest water slide, the park said.

Caleb Schwab, the son of a Kansas state legislator, was killed on Sunday on the Verruckt, a towering water slide at the city's Schlitterbahn water park.

"Since the day he was born, he brought abundant joy to our family and all those who he came into contact with," his family said in a statement.

"As we try to mend our home with him no longer with us, we are comforted knowing he believed in his Savior, Jesus, and they are forever together now. We will see him another day."

The park gave no details on what happened to the boy, except to say the slide was closed after his death.

A park website says two to three people are typically strapped to a raft and then sent down a "jaw-dropping" 51.2m slide.

They are then "blasted back up a second massive hill and then sent down yet another gut wrenching 15 metre drop for the ultimate in water slide thrills."

Riders are supposed to be at least 1.37m tall.

"Given that safety is our first priority, we have closed the Kansas City park today and Monday and have closed the ride pending a full investigation," the park said in a statement.

"Our thoughts and prayers are with the family during this difficult time." The Kansas City Star said the park was teeming with children of legislators and their parents enjoying free passes when the tragedy occurred.

The Verruckt, which means "insane" in German, opened in July 2014.