BENNINGTON, Neb. (WOWT) -- Authorities are investigating an incident Monday morning at Bennington Lake that left three people injured.

Authorities were called to area at 11:09 a.m. after reports that people riding innertubes were in need of help.

Neighbors said it appeared the tubers had hit a wall in the middle of the lake.

Chief Deputy Wayne Hudson with the Douglas County Sheriff's Department said at the scene Monday afternoon that investigators believe a juvenile was driving a boat pulling three people - a 50-year-old man as well as two girls, ages eight and 15 - on innertubes and struck a bridge abutment, the concrete side that holds the island bridge up on the lake.

Hudson said three people were injured and suffering "very traumatic injuries" that likely include brain and spinal injuries as well as injuries to the lower extremities.

A medical helicopter landed at the scene to transport the man to Nebraska Medicine in Omaha. Authorities said it took more than a half-hour to get the adult out of the water and into the medical helicopter.

The two girls were transported from the scene in ambulances.

“People consider these lakes private, but technically the state owns the water, so it’s not a private lake," Hudson said. "So anyone can come out and boat on the lake so long as they can get access to the lake."

There’s a fishing dock and boat ramp access to the lake, he said, but that ramp isn’t technically available to the public.

“When you’re pulling a tuber, you have to be very careful because water is very unpredictable. So are the waves,” Hudson said. “Mindful of the speeds and walls and docks — leave plenty of room away from these obstacles and adjust your speed.”

The investigation will center on what went wrong. Deputies will interview the driver and anyone else on the boat. At the time of the on-scene update Monday, authorities had spoken with one witness but were searching for others who may have seen what happened. They were also looking for any surveillance video that may have captured the incident or events leading up to it.

The crime lab will also take a closer look at the boat, which was removed from the water and is currently in DCSO’s possession.