The Beijing traffic management authority warned people Sunday to stay away from the special vehicles ferrying people between Winter Olympic venues even in the event of a traffic incident.

Personnel involved in the Winter Olympics will be kept in a "closed loop" operation and should avoid contact with people outside it, the Beijing Traffic Management Bureau said in a post on its Twitter-like Weibo account.

If there is an accident with one of the vehicles, people should maintain a safe distance, avoid contact with those inside and wait for professionals to arrive at the scene, the post said.

On Wednesday, organizers said they had begun the "closed loop" operation, in which participants can only leave if they are exiting the country or undergo quarantine, to prevent a COVID-19 outbreak among Games participants from leaking into China's general public.

The 2022 Games, which open on Feb. 4, are set to take place as the world grapples with the highly transmissible omicron variant, although China, which has a zero-tolerance COVID policy, has reported just a handful of omicron cases.

More than 2,000 international athletes are set to come to China for the Games, plus 25,000 other "stakeholders," a large number from overseas. Organizers did not say how many of those people would be in the closed loop.

On Sunday, the coastal city of Tianjin, which borders Beijing, said it would begin testing its population of around 14 million people after at least two cases of the highly-transmissible Omicron variant were detected there.