Meanwhile, a man has been arrested at the scene for prevention of breach of the peace, police said.
PA news agency reported that it was understood that Thomas Taylor, 47, from Rumney, Cardiff, had been arrested after being asked to leave the area.
Speaking before he was arrested, Mr Taylor, a film and TV extra, told PA: "When I heard the reports, I just couldn't believe it could be possible that a car could come off and no-one know they were there.
"I still don't understand it.
"It's natural they might have disappeared for a bit, but the families' instincts are right."
The car was found in the early hours two days after the group went missing after a night out.
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