Refugee arrivals to the Bay Area and communities across the nation are plunging under the Trump administration, even as courts block the president’s effort to halt refugee resettlement, researchers said Thursday.

Nationwide, 3,316 refugees were admitted in April, down two-thirds from October, when 9,945 people were admitted, according to a Pew Research Center analysis of government data. Only four states saw an uptick in resettlements.

In California, 338 refugees arrived in April, down 58 percent from October’s total of 814. The dip — which has alarmed advocates for refugees and prompted questions from some lawmakers — has been particularly striking in Alameda County, data show.

One of a handful of places in California that hosts a significant number of refugees, Alameda County typically welcomes people from Iran, Iraq, Eritrea and other countries plagued by war or human rights abuses. But while 70 refugees arrived between October and January, only nine came in February and March, according to the state Department of Social Services.

“It’s a shame, because people who are eligible for refugee status are the most highly vetted (for security threats) to come into the U.S. compared to other ways of entry,” said Amy Weiss, director of refugee and immigrant services at the Jewish Family and Community Services East Bay, whose organization helps resettle refugees. “It doesn’t really make sense.”

Though courts have so far blocked President Trump’s executive orders — which seek to temporarily bar refugees as well as restrict U.S. entry from a half-dozen majority-Muslim countries — the administration sent a clear signal that it planned to bring in fewer refugees, said Karen Ferguson, the executive director of the International Rescue Committee’s Northern California chapter.

Because of that, she said, government agencies changed their operations and brought people in at a slower pace.

“In order to start to align with the new presidential determination, there has been a decrease in arrivals. It really isn’t more mysterious than that,” Ferguson said, noting that the president has the power to determine the number of refugees allowed in the country, though he has not done so officially outside of the executive orders.

Among the few to make it to the Bay Area was a 28-year-old gay Iraqi named Ali who fled his home country for fear of being killed and came to the U.S. in March. Ali, who lives in the East Bay and asked that his full name be withheld, had been in limbo after Trump signed his first executive order in January, kicking off protests and the court challenges.

“I lost hope,” he said in a recent interview. “It was a miracle when I was finally able to get on the plane. It was a dream to see the runway and take off.”

Refugees became a key point of debate during the 2016 presidential campaign, with Trump at one point claiming that refugees from war-torn Syria represented a dangerous “Trojan horse.” In seeking to freeze the entry of refugees, the president cited security concerns and a need to strengthen vetting procedures for the new arrivals.

In his second executive order, signed in March, Trump sought to suspend the nation’s refugee program for 120 days and cut the number of refugees allowed every year to 50,000 from 110,000. But the order — like the first — was blocked by federal courts.

On Thursday, the Fourth U.S. Circuit Court of Appeals in Richmond, Va., declined to reinstate the revised travel ban, saying it “drips with religious intolerance, animus and discrimination.” The administration will appeal the ruling to the Supreme Court, said Attorney General Jeff Sessions.

Another ruling on the travel ban is expected soon from the Ninth U.S. Circuit Court of Appeals in San Francisco.

Despite the administration’s legal setbacks, “We are still seeing drastic cuts in refugee arrivals and a near-total shutdown in refugee interviews,” said Betsy Fisher, policy director of the International Refugee Assistance Project. “The Departments of State and Homeland Security owe Congress and the American public an explanation of whether and how they are complying with a federal court order.”

The slowdown prompted a group of both Democratic and Republican senators to send a letter this month to Secretary of State Rex Tillerson and Secretary of Homeland Security John Kelly asking how the administration will handle the resettlement process in light of the court opinions.

Citing Homeland Security sources, the Washington Post reported that officials from the agency had ceased going abroad to do interviews of would-be refugees hoping to resettle in the U.S. The refugees must go through a comprehensive approval process — one that can take up to two years — that begins with being referred by the United Nations to the State Department for consideration.

From there, applicants go through interviews with multiple agencies, including Homeland Security.

So far in the 2017 fiscal year, which ends in September, more than 42,000 refugees have been admitted to the U.S. — well below the 110,000 that resettlement organizations had expected before the election, according to the Pew Research Center analysis.

If Trump’s desired ceiling of 50,000 refugees were to be fulfilled this year, advocates said, many people would be left in difficult or deadly situations.

“That’s 60,000 people who potentially may not be brought in — that’s a significant change in the number of human beings brought into this country,” said Ferguson of the International Rescue Committee. “It can end up in a tragic result for those individuals — they are scraping for survival every day.”

Hamed Aleaziz is a San Francisco Chronicle staff writer. Email: haleaziz@sfchronicle.com Twitter: @haleaziz