(TNS) — President Donald Trump issued several orders to dramatically toughen immigration standards and enforcement within hours of taking office on Monday, declaring a national emergency at the southern border after having promised earlier in the day to quickly begin deporting “millions and millions” of people.

“All illegal entry will immediately be halted,” he said in his inauguration speech. “I will send troops to the southern border to repel the disastrous invasion of our country.”

Pro-immigrant groups in Philadelphia promised a fight, insisting they would stand up for migrants and families who seek to make their way in a new country.

“VietLead stands committed and ready with all immigrant and racial-justice groups in Philadelphia, Pennsylvania, and across the country,” the Vietnamese-led organization said in a statement. “Our families must remain united, our communities must remain intact.”

On a bitter cold afternoon, Marcy Boroff, 61, gathered with about 100 demonstrators outside of the Philadelphia ICE office at Eighth and Cherry Streets, saying she was there “for the future generation.”

“It’s important to do something, to be with people that are fighting and calling out racism and fought the system,” she said, rubbing her knitted mittens against each other.

Incoming White House officials told reporters that Trump would issue orders to suspend U.S. refugee resettlement for at least four months and to end asylum. Orders were still being posted on the White House website Monday night.

Trump signed an order to end birthright citizenship, which has been enshrined in the Constitution since the end of the Civil War. That order would end automatic citizenship for children born in this country to undocumented people.

He also signed an order declaring a national emergency at the U.S.-Mexico border. And another order saying it would be U.S. policy to have the armed forces prioritize “the protection of the sovereignty and territorial integrity of the United States” along its borders.

“As Commander in Chief,” Trump said during his inauguration speech, “I have no higher responsibility than to defend our country from threats and invasions and that is exactly what I am going to do. We will do it at a level that nobody has ever seen before.”

Many people support Trump’s immigration policies, including his plan for mass deportations.

A new poll by Ipsos and The New York Times shows that 63% of those surveyed supported deporting immigrants who entered the country without permission during the last four years, and 55% said they supported deporting all immigrants who are here illegally.

Another Trump order issued on Monday night directed government agencies to undertake “enhanced vetting” of all people — the order called them “aliens” — seeking admission to the United States.

Immigrant advocates in the Philadelphia area have braced for a Trump presidency, particularly his stated plans to deport millions of undocumented people living in the United States. About 13 million people, roughly the population of Pennsylvania, are living in the country without legal permission.

On Monday, Trump pledged to invoke the Alien Enemies Act, a 1798 wartime authority, having on the campaign trail promised to put “these vicious and bloodthirsty criminals in jail, then kick them the hell out of our country as fast as possible.”

The Brennan Center for Justice at the New York University School of Law calls the act “one of the most notorious laws in U.S. history,” an overbroad authority that may violate constitutional rights in wartime and is subject to abuse in peacetime.

The act allows the president to detain or deport citizens of an enemy nation, targeting immigrants without a hearing, based on nothing more than their citizenship or country of birth, according to the center. The law was passed to prevent espionage or sabotage during war, but can be wielded against immigrants who have done nothing wrong and are lawfully present in the United States, the center said.

Make the Road Pennsylvania, one of the state’s largest immigrant-rights groups, said Monday marked the beginning of a challenging four years for immigrants and working families.

“Trump’s fascist and hateful agenda requires despair to thrive, and the word ‘hopeless’ is not in our vocabulary,” the group said in a statement. “We won’t back down. The resilience of people committed to fighting against oppression and defending immigrant communities in this country has never been reliant on who is in the White House.”

At the Ethical Society on Rittenhouse Square in Philadelphia, about 200 people skipped watching the inauguration and gathered for a concert put on by immigrants and refugees.

“Raise your hand if you are a descendant of Native Americans. Right. That’s what I thought. Immigrants are us. Right here in this room,” Cathryn Miller-Wilson, executive director of HIAS Pennsylvania, told the crowd.

The concert, organized by HIAS Pennsylvania and BuildaBridge, sought to celebrate diversity in the spirit of Rev. Martin Luther King on the holiday that honors his life.

“We are here for you,” said Ami Yares, executive director of BuildaBridge, as musicians from Iran, Brazil and other countries took the stage. “You are not alone.”

On Monday Trump immediately ended the use of an important border app called CBP One, the initials for U.S. Customs and Border Protection, that has allowed nearly a million people to legally enter the United States with permission to work.

The app let migrants schedule appointments at eight southwest border ports of entry. Critics said the app was a magnet that encouraged people to come to the Mexican border to try to enter the United States.

On Monday an online notice said existing appointments have been canceled.

The Pennsylvania Immigration Coalition, an advocacy organization, said it’s working with other groups to set priorities for ways to defend and promote immigrant rights across the state.

“The years to come will be extremely difficult and at times devastating,” the coalition said in a statement. “Members of the Pennsylvania Immigration Coalition will stay the course for the systemic solutions the immigrant community deserves.”

Priorities include ending medical deportations statewide and passing a law that allows drivers licenses for all, a measure long stalled in the legislature.