Cruise ship passengers ended up in the Mississippi River on Friday when an oil tanker hit the side of the ship and capsized it.

Video captured the wild scene, which took place near New Orleans ... and shows the tanker -- Atlantic Asphalt -- running directly into the side of American Heritage, the river cruise ship.

It's unclear why the tanker ran into the ship at this time ... but it hit the ship hard enough to flip it on its side -- and reports say multiple passengers were flung into the water, where they were later rescued.

The ship slowly sank while authorities rushed to the scene. The Port of New Orleans states that 150 people were aboard the cruise at the time of the accident.

American Heritage was docked at the Crescent City Connection bridge when Atlantic Asphalt ran into it.

It's unclear how many people -- if any -- were injured in the collision.