US airports have been thrown into chaos as new coronavirus health screening measures for people returning from Europe come into force.
Long queues formed as travellers waited for hours for the screenings before passing through customs.
Earlier, Vice-President Mike Pence said a ban imposed on travel from European nations would be extended to the UK and Ireland on Tuesday.
The US has more than 2, confirmed cases, with 55 deaths.
Correspondents say there is a growing sense of unease and confusion in the US, with fears of a run on hospital beds and concern about childcare as tens of millions of students are sent home from school .
In other developments:
for a tweet , since deleted, showing selfies with his family at a crowded restaurant
What has been happening at the airports?
At Chicago O’Hare and Dallas DFW airports, passengers reported long queues as travellers returning from Europe waited to be screened as part of measures to combat coronavirus.
The US administration has imposed a ban on non-Americans traveling from the European countries in the Schengen free movement zone, which will be extended to the UK and Ireland as of Tuesday.
US citizens are allowed to return but face screening.
Illinois Governor JB Pritzker said the long lines at O’Hare were “unacceptable”.
People have been tweeting pictures and videos of passengers waiting to be processed, forming large crowds in airport terminals:
Passengers are being questioned about their medical histories and checked for symptoms.
Paige Hardy, a US graduate student returning from London, told the New York Times there was alarm on her flight to Dallas after a series of confusing announcements.
“It truly felt like an apocalyptic scenario,” she said.
In New York , there were reports of a flight from Paris being boarded by customs agents wearing masks. (Acting Homeland Security Secretary Chad Wolf said his office was working with airlines to improve screening times.
Some public health experts have noted that waiting in crowded terminals could possibly lead to more people becoming infected with the virus.
On Friday, President Trump declared a national state of emergency to release $ (bn) £ 54 bn) to fight the spread of the virus.