A waterspout uprooted an inflatable bounce house with three children inside it on a South Florida beach Monday, sending it flying above palm trees, across a parking lot and over four lanes of traffic, police said.

All three children were injured but were alert and conscious when they were taken to a hospital, Fort Lauderdale Police spokesman Keven Dupree said. Additional information about the children or their conditions was not immediately known.

Video on local television stations showed the waterspout — a whirling column of air and water mist — moving from the ocean onto the sand of Fort Lauderdale beach, tossing a canopy and rolling the bounce house before lifting it into the air.

The house flew above the tree line, but the children appeared to have fallen out when it first flipped over the beach, Dupree said.

"They were immediately dropped out of the bounce house onto the sand," he said.

The bounce house had been secured to a basketball court as part of a city-sponsored family activity zone set up for the Memorial Day holiday. The waterspout snapped a concrete pole holding a basketball hoop.

Burt Osteen, a 37-year-old flooring installer from Fort Lauderdale, and his family dove to the sand on their stomachs as they saw the waterspout spinning toward them.

"It came right over us. We laid on the ground; we were right in front of the bounce house. We watched it pick up the bounce house and snap a basketball hoop," Osteen said.

He barely felt anything, though, when the waterspout passed over them. The tablecloths on nearby picnic tables weren't even disturbed by the wind, he said.

"The only thing was the sand, getting stung by the sand," he said.

Unlike tornadoes, waterspouts don't need thunderstorms for their funnel clouds to form. On Monday afternoon, a band of clouds was moving in from the ocean had winds favorable for waterspout formation, said Jeral Estupinan, a meteorologist with the National Weather Service in Miami.

"It developed very close to the coastline and moved onshore, and it dissipated very quickly onshore, like any other waterspout," Estupinan said.