A former TV producer behind BBC naturalist Sir David Attenborough’s wildlife documentaries went completely off the rails on a family during a road-rage incident, claiming he wanted one of them “dead,” shocking cellphone video shows.

“Planet Earth” producer Fergus Beeley was caught on camera Saturday as he launched the explosive outburst against a family, which included an 11-year-old boy, in a parking lot in Hampshire, England.

In the 4½-minute clip posted on YouTube, an aggressive Beeley can be heard shouting at the family as he pops his head inside their car.

At points, Beeley shouts that he’s putting members of the family, including the child, “under a citizen’s arrest” and yells for the driver, identified by local media as 33-year-old Simon Gale, to “get back in the car before you die!”

The video begins with Beeley mouthing off to the family while one woman in the car says that Beeley claimed he was a cop.

“I wouldn’t say that to a bunch of wankers like you,” Beeley says.

According to a woman speaking in the video, Beeley claimed he was an off-duty police officer and later on the woman says to Beeley: “You said you wanted us dead!”

“I do want you dead! In fact, I want you dead right now!” Beeley fires back.

“Get back in the car before you die!” Beeley threatens Gale as he tries to yank open the car door, the video shows.

While grabbing Gale by the arms and pushing him against the car, Beeley shouts: “You’re under a citizen arrest! Put your hands on the car … and get ready to die!”

Police were called and both Beeley and Gale made allegations of assault, but neither pursed a formal complaint, according to local reports.

Gale said Beeley grabbed him by the neck and “raised his fist in a threatening manner,” according to the Daily Mail.

“It was quite a scary thing. He flew into an absolute raving state. When he got out the car he demanded, ‘Do you know who I am?,’ and when I said I didn’t, he grabbed me and pushed me against the car,” Gale said, according to the UK news outlet, adding that Beeley tried to push his mother-in-law into traffic.

Gale said just before Beeley’s tirade, his car ended up colliding with another car and “we almost got knocked into the outside lane.”

“We pulled over to the side of the road and my wife got out of the car to exchange insurance details with this woman — I didn’t really think anything of it at the time,” Gale said. “Then Fergus Beeley pulled up behind us in a different car and started screaming and shouting at us.”

The father added that his son was traumatized by the incident.

“’My son was so scared by it that he actually ended up sleeping in our room last night. He’s very shaken,” Gale said. “Luckily none of us are harmed in any way — but we’re still quite shaken by it. We’re definitely going to be a bit more cautious from now on.”

Beeley was a longtime producer for the BBC and helped produced some Attenborough’s award-winning wildlife documentaries such as “The Life of Birds.”

He did not respond to a request for comment from the Daily Mail.