Tourists visiting border wall get stranded by California river. One is from Idaho.

A father and son visiting California were rescued from floodwaters Thursday after getting stranded in their truck during a trip to the United State-Mexico border wall, authorities said.

The men got stuck at roughly 9 a.m. on a road flooded by the Tijuana River in Imperial Beach, according to FOX 5 San Diego, which reported that “helicopter video showed one of the men sitting on top of a red pickup truck surrounded by water as rescuers gathered on the dry end of the street.”

Authorities said the road the men were found on was closed, but “the pair drove around a sign informing them of the closure” and their truck was carried away in five feet of water, FOX 5 reports.

The son, a 49-year-old from North Dakota, managed to crawl out of the flooding truck and walk through the river water to safety, NBC 7 San Diego reports. But his father, a 75-year-old retired U.S. Marine from Idaho, was trapped on top of the almost fully submerged Toyota Tacoma until San Diego Fire Department rescuers reached him, video shows.

NBC didn’t identify either man by name. The TV station reported that the men “wanted to check out the border wall in San Ysidro during their trip to San Diego.”

Fire officials said the men “estimated that this was moving about three miles an hour and that’s plenty enough to take a person downstream — and if they got caught in the downstream side of the Tijuana River, it’s going to be very difficult to rescue them,” according to CBS 8.

The men’s truck “made it halfway across before it got stuck in the water” in the flooded area on Saturn Boulevard, according to KGTV.

The father told NBC that “the water didn’t look that deep.”

But authorities advised against driving through standing water of uncertain depth.

“It’s not safe, any amount of water you are going to drive through you do not know how deep it is, or how fast it’s moving. So, we advise people again and again don’t drive through these, there is always a way around,” San Diego Fire-Rescue Battalion Chief Michael Howell told NBC.

No one was hurt, but the truck wasn’t able to be pulled out right away because of the high water, CBS 8 reports.

Officials said the truck will have to say there until flood waters go down, according to KGTV.

Rescuers had to undergo “a multi-step decontamination process” following the rescue because they had waded in the possibly polluted river water, KGTV reports.