Rome announced a sweeping quarantine on Sunday, restricting the movements of about 16 million people or a quarter of its population in an effort to limit contain the virus’ spread and end its advance at the source of western Europe’s outbreak.

After midnight, Prime Minister Conte signed an executive order that will affect approximately 16 million people in the nation’s north, including the Lombardy region as well as 14 provinces in neighboring regions. The emergency measures will be effective on April 3.

“For Lombardy and for the other northern provinces that I have listed there will be a ban for everybody to move in and out of these territories and also within the same territory,” Conte said. “Exceptions will be allowed only for proven professional needs, exceptional cases, and health issues.”