Virginia Gov. Ralph Northam (D) warned on Friday that the state is experiencing “a concerning increase” in coronavirus cases in Hampton Roads, a region with beach attractions and soaring infections among young people.

The state’s number of new cases outside that region has been mostly steady after steep declines stalled in mid-June, but eastern Virginia has gone in the other direction. The spike is especially notable in Virginia Beach, which on Friday added 116 cases — nearly double the daily high reached earlier in the week, and triple the previous peak of 37 on June 1.

Health officials in the city, known for its long boardwalk and oceanfront high-rises about an hour from the North Carolina border, say some young people have resisted wearing masks and, once infected, refused to cooperate with contact tracers. Coronavirus cases in the city for those age 29 and younger are up almost 250 percent since the last week of May.

Northam, who resisted pressure from Virginia Beach business interests to open beaches before Memorial Day weekend, expressed concern at a free coronavirus testing event Friday in Chesapeake. He said he will continue to monitor the region’s health metrics and “won’t hesitate to impose restrictions if needed.”

“So far, Virginia has avoided the same spike in #COVID19 cases that other states are experiencing, but we are starting to see a concerning increase, particularly in Hampton Roads,” Northam later tweeted. “We all have to stay vigilant — we have come too far to let our guard down now.”

The increases in that region come as numbers for covid-19, the disease caused by the novel coronavirus, have held relatively steady for the rest of Virginia and the national capital region as a whole. The District, Maryland and Virginia on Friday added 1,470 new coronavirus cases, with each jurisdiction topping its seven-day average. The three localities reported 36 additional deaths.

The largest daily increase came in Virginia, where 943 new cases were reported — the state’s highest jump in a single day since June 7. The state also added 21 fatalities. Maryland reported 463 known cases while adding 15 deaths. The District added 64 cases and no deaths.

Virginia Beach has come roaring back since the early days of the shutdown.

Merchants who suffered through late spring with a nearly deserted oceanfront worked with Northam’s office to have beaches reopened by Memorial Day weekend. The city hired a workforce of “ambassadors” to roam the resort area and encourage good hygiene.

By last week, the oceanfront area looked close to normal for summertime. Sunbathers crowded the sand and sat together on boats headed out for parasailing. While some coffee shops continued to keep patrons outside, hotels were packed, with few masks in sight.

“It’s tourist season and people got out of the house and came to the beach,” said Erin Sutton, emergency services director for the city of Virginia Beach.

Sutton warned the city council earlier this week that Virginia Beach is seeing an increase of cases tied to “congregate facilities” such as restaurants and other businesses. The seven-day average of new cases had hit 40, up from 11 at the beginning of June — and had grown to 58 on Friday. The percentage of tests coming back positive had risen to 5.4 from 3.1 a week ago.

The percent positivity rate has been increasing among all ages in Virginia Beach, but most sharply among those between the ages of 20 and 29, according to data from the Virginia Department of Health. The rate is 9.7 percent for that age group, on track to overtake the highest, 10- to 19-year-olds, which are at 9.8 percent and trending downward, the data show.

“Wearing masks is not as consistent” among young people, Sutton said. “They’re getting out and socializing and crowding into restaurants or going to someone’s house and hanging out.”

She told city leaders that contact tracers reported “a disturbing trend of cases not providing names of close contacts so that contacts can be notified, and some [are] being uncooperative in agreeing to participate in monitoring.”

Complaints are up about restaurants and bars not following social distancing rules, she said, and the city is working to emphasize the need to follow the requirements.

“It’s a challenging time because you have some people who are absolutely not going to wear [masks],” Sutton said. “It is a concern because we want to see covid cases continue to decline. We don’t want to be a hot spot.”

Russell Lyons, president of the Virginia Beach Hotel Association, said his members have signed a “gold standard pledge” promising to follow healthy practices.

“We want to protect our guests, of course, but also want to protect our associates and make them feel comfortable going home at night to their families,” said Lyons, whose family owns several oceanfront hotels. His employees wear masks and stand behind sneeze guards at the front desk, among other precautions, he said.

“Certainly there’s always going to be the one-off or someone not doing their part, but I think by and large we’re being very responsible as a hotel community,” he said.

Big public events continue to be canceled. This past week, the city’s Neptune Festival pulled the plug for the year, and a sand soccer tournament was scratched.

Sutton is bracing for a possible spike from the July 4 holiday weekend, which could start to become apparent in test results toward the middle of next week. She’s not ready to sound the alarm just yet, noting that lags in testing and other factors make numbers rise and fall.

“For me it’s just like following the track of a hurricane — it wiggles to the left, wiggles to the right, and where it’s going to end up you’re not sure,” she said.

Northern Virginia elected leaders said Friday that they are carefully watching medical data and conferring with their own health directors and each other as the coronavirus pandemic evolves.

Northern Virginia’s daily caseload has changed little since mid-June, with a seven-day average hovering near 160. Excluding Northern Virginia, the state’s average daily caseload during that time has risen from about 330 to 480.

“We would support any additional restrictions [Northam] might impose,” said Jeff McKay (D), chairman of the Fairfax County Board of Supervisors. “Our message to the public has not changed at all — wash your hands, keep a safe distance and stay home if you can. No matter what the governor does, no matter what we do, most of the success will be in the hands of the people.”

Phyllis Randall (D), chair of the Loudoun County Board of Supervisors, said her county has room in its hospitals, enough ventilators and enough personal protective equipment to handle coronavirus  cases.  The  county   spent $9 million of its $30 million Cares Act funds for personal protective equipment and has tried to distribute it widely, she said.

“We are strongly encouraging people to wear masks,” Randall said.

Alexandria has targeted testing in neighborhoods with high reports of coronavirus infections and is working to ensure compliance with existing mask requirements and distancing rules, Mayor Justin Wilson (D) said.

Arlington County Board Chair Libby Garvey (D) added that “clearly any leader is watching” Virginia’s reports closely to make sure cases don’t spike locally and to be sure localities meet standards set by the state to keep the virus under control.

“The more we get on the same page with Maryland and D.C., the better. . . . This has to be a team effort,” McKay said. “I’ve been in every corner of this county and I’ve been impressed that people are doing the right thing with distancing and masks. One area of concern is the uptick in traffic, which means fewer people are staying home, but as long as they are being responsible, I’m impressed.”

Patricia Sullivan contributed to this report.