Leaders of Maryland’s most populous jurisdictions pushed for unified shutdowns Wednesday to curb the surging coronavirus as some reimposed the toughest restrictions since the spring.

Montgomery County Executive Marc Elrich (D) proposed banning all indoor dining, hours after Baltimore City forbade any dining at restaurants, indoors or outdoors. The city’s new protocols are the strictest in Maryland since shutdowns during the first wave of infections.

Another wave of restrictions will follow in the region Thursday, when Virginia Gov. Ralph Northam (D) and at least one more Maryland county have planned announcements.

The new restrictions came as the ­seven-day average of new daily infections surged to a record Wednesday across the greater Washington region. Maryland, Virginia and D.C. each recorded new highs in their recent caseloads.

In Maryland’s most populous jurisdiction, Elrich’s executive order would eliminate indoor dining and cut capacity at retail establishments to one customer per 200 square feet — a change from one customer per 200 square feet or 25 percent capacity. The order also states that nonprofessional sports are “social gatherings,” limiting them to 10 people indoors and 25 people outdoors.

Elrich announced the order on a call with leaders of the state’s eight largest jurisdictions. It still must still be approved by the Montgomery County Council, which has not previously rejected proposed restrictions in the county.

The council is scheduled to vote on the order Tuesday, and if approved it would go into effect at 5 p.m. that day.

The council’s new president, Tom Hucker (D-District 5), said Wednesday that he was still reviewing the order with colleagues and soliciting feedback from residents. He noted, however, that the council has been “very supportive of our top health officials.”

“The trends in our cases and in our entire region are certainly extremely concerning,” he said.

Leaders of the eight Maryland jurisdictions, whose residents constitute 75 percent of the state’s population, said they hosted the joint news conference Wednesday, the first of its kind since the pandemic began, because the state is at a pivotal moment, with cases, hospitalizations and deaths rapidly rising.

“We have to work together,” said Prince George’s County Executive Angela D. Alsobrooks (D). “Coronavirus does not know borders.”

Other leaders stressed the importance of regional cooperation, with Anne Arundel County Executive Steuart Pittman (D) urging Gov. Larry Hogan (R) to roll out a tougher statewide strategy to address the surge.

“I certainly believe that this should be done statewide, because we have one health-care system in the state,” Pittman said, adding that he plans to announce additional restrictions Thursday. “We can stop this virus in its tracks in Anne Arundel County, but our two hospitals would still have patients coming in from other counties.”

Pittman said that Hogan understands “what is at stake here” and that he expects county leaders will continue talking with one another and Hogan about next steps.

“We’re going to look back, I think, on this time and we’re going to wonder if we did everything that we could to save as many lives as possible,” Pittman said.

Harford County Executive Barry Glassman, the sole Republican among the eight leaders, pledged to closely monitor data and take more actions if necessary. He urged residents to continue to practice “personal responsibility” by wearing masks, washing their hands and practicing social distancing.

The phone call came hours after Baltimore’s new mayor announced the most restrictive coronavirus measures in the state, including shutting down all indoor and outdoor dining.

Mayor Brandon Scott (D) said tougher restrictions on places where the virus is most likely to spread must be implemented to stave off a catastrophe at hospitals. The restrictions, which go into effect at 5 p.m. Friday, also shut down bar service, movie theaters, adult entertainment venues and hookah bars.

Scott said more restrictions could be added if the city’s infection rate does not abate.

“Baltimore, we’re still in a pandemic. And to be honest, some of us aren’t acting like it,” Scott said during his first public appearance since being inaugurated Tuesday.

He also capped capacity at 25 percent for religious institutions, retail establishments, hair salons and barbershops, gyms, the Maryland Zoo and the city’s casino, which is also prohibited from selling food and drinks. All indoor public and private gatherings will be limited to 10 people, with outdoor gatherings capped at 25.

Collectively, the restrictions are the most far-reaching in Maryland since officials began lifting shutdown measures in the spring.

“Based on our current trajectory of cases and hospitalizations, projections show our hospitals will be overwhelmed if we do not act,” Scott said. “I am not afraid to do the right thing over the popular one. This is about saving lives — nothing more, nothing less.”

Statewide and in Baltimore, the daily coronavirus infection rate has tripled since Nov. 1, rising from about 14 people per 100,000 residents to 45 as of Wednesday.

The state broke a record Wednesday for coronavirus-related hospitalizations that had stood since May, with 1,715 people needing treatment. The number of hospitalized patients has increased 22 percent in the past week and 143 percent in the past 30 days.

The surge in hospitalizations has strained Maryland’s already swollen hospital system and forced some institutions to shuffle patients to less overwhelmed hospitals — but those are also filling up.

As of Wednesday, more than half of Maryland’s 44 hospitals had 90 percent of their staffed intensive-care or acute-care beds full, according to state officials. Last week, 34 patients were moved out of 17 hospitals that did not have the capacity to treat them.

Infections from the Thanksgiving holiday week have begun to show up in the region’s tallies. The total number of cases in Virginia, Maryland and D.C. stood at 513,635 on Wednesday, while the seven-day average of new daily cases hit a record in each jurisdiction.

In Virginia, Northam will announce Thursday that he will tighten restrictions in the state, spokeswoman Alena Yarmosky said. She said the governor will announce “mitigation measures” that will be “nuanced and in line with our targeted, data-driven response” but declined to be more specific. Northam’s new protocols will come one day after Virginia set a single-day record for new infections.

As the virus continued to spread, two more inmates in the Arlington County detention center tested positive this week, six days after the first known case was reported at the jail. Everyone known to be exposed has been tested, Maj. Tara Johnson said, but the jail is aiming to test its entire staff and inmate population by the end of the week.

The three inmates are being treated within the jail, and authorities said they are doing well. They have been interviewed by public health authorities, but all three have been in the jail for more than two months and no source of the outbreak has been identified.

In the District, Health Director LaQuandra Nesbitt told the D.C. Council on Wednesday that she expects the first doses of a vaccine from Pfizer to begin arriving in the city next week. Those doses will go to five hospitals — George Washington University Hospital, MedStar Washington Hospital Center, Howard University Hospital, Children’s National Hospital and MedStar Georgetown University Hospital — which will share them with other city hospitals to be administered to high-priority health-care workers.

Nesbitt also sought to explain the Bowser administration’s decision this week to suspend all high school sports but to allow younger children to continue practicing no-contact sports in small groups.

Coronavirus cases linked to high school sports, Nesbitt said, have arisen from group activities that high school teams participate in, not necessarily on the playing field. “Even among low-contact sports, there are outbreaks among student athletes, and it is not just the sport itself,” she said. “It’s the activities they do as student-athletes that creates risk.”

Interviews with athletes who got the virus prompted the city to decide to shut down high school sports entirely, while concluding that younger children can be closely supervised and play safely, Nesbitt said.

Rebecca Tan, Laura Vozzella and Rachel Weiner contributed to this report.