A cruise ship collided in deep fog with a container ship off Vietnam, punching a hole in the container ship and knocking passengers off their feet, a passenger told CNN Monday.

“The foghorn at the back of the ship had been going off consistently, throughout the morning,” passenger Andrew Lock said Monday from Hong Kong about the incident, which occurred last Friday morning when the Silver Shadow was about five miles from the coast.

“But there was a certain point in time when the foghorn at the front of the ship suddenly sounded. And it was much, much louder. And it caused us to look up. And in fact we looked up straight out of the window,” he said.

“And through the fog, to our horror, we saw this Vietnamese container ship appear, sideways on. And it was as if our ship was perfectly lined up to hit it in the side.”

Click here for the full report from CNN.