San Juan (AFP) - Puerto Rico was under 24-hour isolation Monday, governor Wanda Vazquez told local media, leaving the island the first major US jurisdiction to take such drastic measures against the coronavirus pandemic.

"All citizens should stay in their homes 24/7 until March 30," Vazquez told WKAQ 580 AM radio.

The comments came a day after she announced by video message a 9:00 pm to 5:00 am curfew, and the different directives left some residents confused about whether or not they could go out in the daytime.

On Monday Vazquez said that, during the day, only authorized persons and those seeking food, gasoline or medical services can circulate but "from 9:00 at night it's a lockdown," she said.

"If someone needs to go to the pharmacy, if they need to go to the supermarket, or to get gasoline for their vehicles, it can be done from 5:00 in the morning until 9:00 at night," she said on the radio.

Other than such essential trips, she added, "you have to stay at home."

The Caribbean territory of 2.9 million, whose residents are US citizens, was the first to adopt such a major restriction, although New Jersey will implement a night-time curfew from Monday night, and a "remain-in-place" order will take effect from Tuesday in San Francisco.

Puerto Ricans were still trying to understand the restrictions in their territory.

"People have so many questions," Aliana Diaz, 54, a marathon runner, told AFP.

She said her son, visiting from the US mainland, thought he could go out during the day.

"I told him he can't do it."

Until Sunday, Puerto Rico had reported five cases of the new coronavirus, which has infected more than 4,000 people in the entire US, killing 74 people, according to a tally by Johns Hopkins University.