(CNN) It was early Saturday morning when federal agents knocked on Rene Morales' door.

He didn't open it. Instead, he hid with his sister, her three children and two other friends inside a bedroom, ignoring the banging until the agents left about an hour later.

By midmorning, Morales said, the agents caught up with him while he left to run an errand, persuading him to allow them to search the house to look for a fugitive Morales said didn't live with him.

Morales let them in. Soon, it became clear his sister Rosa and two of her children were the real target of the immigration agents.

"They were coming for my family," Morales said.

Now, days later, he's still trying to figure out the details of their fate. He said he believes they were part of a series of raids nationwide targeting immigrants who were part of the wave of children and families who crossed into the United States illegally in summer 2014.

Their detention was soon reported by Atlanta newspaper Mundo Hispanico, which documented eight cases in the area of women with children taken into custody by Immigration and Customs Enforcement agents and brought to a staging area at a local mall.

A spokesman said the agency doesn't comment on specific cases, but acknowledged the arrest occurred at the time of the operation.

'This should come as no surprise'

The raids had been rumored for days after a report in The Washington Post revealed that immigration authorities were planning a nationwide sweep this month.

Department of Homeland Security Secretary Jeh Johnson said Monday that 121 people were taken into custody, mainly in Georgia, North Carolina and Texas.

"As I have said repeatedly, our borders are not open to illegal migration; if you come here illegally, we will send you back consistent with our laws and values," he said.

The focus of the operation, he said, were adults and their children who were apprehended after May 1, 2014 after crossing the southern border illegally, were issued orders of removal by an immigration court and have exhausted "appropriate legal remedies."

The new push to detain and deport undocumented immigrants drew swift criticism from activists.

"Raids that terrorize communities, trample civil rights and separate families are something we would expect from a President Trump. The very tactic -- with teams of ICE officers showing up at someone's home, unannounced, using deception to gain entry, waking up sleeping children and carting away both parents and kids -- is repugnant," said Frank Sharry, executive director of America's Voice. "When this happened during the Bush presidency, then-candidate Obama denounced it. The fact that it is happening now under a President Obama is outrageous."

The American Civil Liberties Union issued a statement condemning the raids, describing them as "a scare tactic to deter other families fleeing violence in Central America from coming to the United States."

Cecillia Wang, director of the ACLU's immigrants' rights project, said the U.S. immigration system was rigged against the families from the start.

"Many of these mothers and children had no lawyers because they could not afford them," she said. "Without counsel, traumatized refugees don't understand what is happening in court and cannot get their legitimate asylum claims heard."

'Don't open the door,' foreign ministries warn

As word of the impending raids spread, diplomats from Guatemala and El Salvador posted warnings on their websites over the weekend.

"Immigration agents must show you an order signed by a judge to enter your house," El Salvador's foreign ministry said in a statement posted on its Twitter account . "If they don't have one, you don't have to open the door."

Guatemala's foreign ministry warned people not to be fooled.

"Don't open the door to strangers who say they're looking for someone else," the ministry's statement said

Awaiting deportation

According to U.S. Border Patrol figures , more than 100,000 people who were part of so-called family units -- parents with children -- entered the United States illegally through the country's southwestern border since 2014.

Many of them seek asylum in the United States. Out of more than 41,000 asylum requests fielded by the U.S. Department of Justice Executive Office for Immigration review in 2014, 8,775 were granted

Rene Morales said his sister Rosa and her children were captured by immigration agents in Houston after they crossed illegally in July 2014.

Over the weekend, U.S. immigration authorities detained Rosa Morales, shown here at a recent celebration.

Three days later they were released and headed to Atlanta, where they hired a lawyer to help with their asylum claim. The family escaped Guatemala, he said, after a kidnapping attempt. In March 2015, a judge signed an order of removal.

Their lawyer has been trying to fight it.

But as of Tuesday afternoon, it seemed like for many of his family members, time in the United States was running out.

One of Rosa's daughters, who gave birth to a child in the United States shortly after her arrival, wasn't taken into custody by the agents over the weekend.

But Rosa Morales and her other children were at a detention center in Texas on Tuesday, waiting to be deported.