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SAN DIEGO — The federal government, in the most complete statistical snapshot of immigration enforcement under President Donald Trump, says arrests by deportation officers soared while Border Patrol arrests have plunged to a 45-year low.

The Border Patrol made 310,531 arrests during the fiscal year that ended Sept. 30, a decline of 25 percent from 415,816 a year earlier and the lowest level since 1971. Despite the significant decline, arrests increased every month since May — largely families and unaccompanied children.

Immigration and Customs Enforcement, whose officers pick up people for deportation away from the border, made 143,470 arrests, an increase of 25 percent from 114,434 a year earlier. After Trump took office, ICE arrests surged 40 percent from the same period a year earlier.

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The numbers released by the government Tuesday show that deportation officers are taking Trump's call for an immigration crackdown to heart, even without the funding increase that the president has sought from Congress for more hiring. In February, then-Homeland Security Secretary John Kelly scrapped the previous administration's instructions to limit deportations to public safety threats, convicted criminals and recent border crossers, effectively making anyone in the country illegally vulnerable.

"We have clearly seen the successful results of the president's commitment to supporting the frontline officers and agents of (the Department of Homeland Security) as they enforce the law and secure our borders," said Elaine Duke, acting secretary.

ICE said that deportations totaled 226,119, a decline of 6 percent from the previous year, but that number masks a seismic shift away from the border. ICE often takes custody of people at the border before deporting them; the sharp drop in Border Patrol arrests means fewer people to remove.

ICE said "interior removals" — people deported after being arrested away from the border — jumped 25 percent to 81,603 from 65,332 the previous year. They rose 37 percent since Trump's inauguration compared to the same period a year earlier.

Reasons for the precipitous drop in border arrests are unclear but Trump's election may have deterred people from trying. Trump has yet to get funding for the first installment of his proposed border wall with Mexico and the number of Border Patrol agents has declined as the government's struggles to fill vacancies continues under his presidency.

About 58 percent of Border Patrol arrests were people from countries other than Mexico — up from 54 percent a year earlier — largely from Central America. Starting around 2011, large numbers from El Salvador, Guatemala and Honduras began entering the country in South Texas, which replaced Arizona as the busiest corridor for illegal crossings.

Ronald Vitiello, Customs and Border Protection's acting deputy commissioner, said he was "very concerned" about increases in families and children crossing in recent months. During the fiscal year, which included the President Barack Obama administration's final months, border authorities stopped people traveling as families 104,997 times on the Mexican border and unaccompanied children 48,681 times.

CBP also said inspectors at land crossings, airports and seaports denied entry 216,370 times during the fiscal year, a decline of 24 percent from 2016. Border Patrol arrests occur outside of those official points of entry.

CBP, which has faced allegations of excessive use of force, said its employees used firearms 17 times during the fiscal year, down from 27 the previous year and 58 in 2012. It said its employees were assaulted 847 times, compared to less than 600 each year going back to 2012.