(CNN) The mother rushed toward her son the second he stepped off the jetway. Then she teared up.

In the waiting area of Gate C14 at Baltimore Washington International Airport, she wrapped a blanket around him, cradled his head in her arms and wept.

"I love you," she said in Spanish, between sobs.

It had been more than a month since Beata Mariana de Jesus Mejia-Mejia had seen her 7-year-old son, Darwin. Authorities, she said, separated them at an immigration holding facility in Arizona days after they crossed the US-Mexico border.

This week, the 38-year-old Guatemalan mother sued several government agencies and top Trump administration officials, asking a federal judge to order authorities to release her son.

Beata Mariana de Jesus Mejia-Mejia sued the government, asking to be reunited with her son.

Lawyers announced in court Thursday that an agreement had been reached just minutes before a hearing in the high-profile case was to start. A few hours later, Darwin was released from a shelter in Phoenix, Arizona, and headed toward Washington, where his mother had traveled to make her case in federal court.

Mejia met her son at the Baltimore airport gate early Friday, accompanied by members of her legal team, who broadcast a live video of the tearful reunion on Facebook.

By the time she and her son made it to baggage claim, where a throng of reporters waited, Mejia was smiling as they walked side by side. But she told reporters she could tell her son was still sad.

Darwin looked up at his mother, his lip quivering. She leaned down and kissed him on the cheek.

'A knife in your chest'

Mejia told CNN this week that she'd been trying to learn her son's whereabouts for weeks. But no one had given her a clear answer.

Mejia says she took this selfie of her and her son at their church in Guatemala.

"It's not fair for a mother," she said. "It's like they're putting a knife in your chest and killing you."

Mejia says she and her son came to the United States seeking asylum, fleeing death threats and domestic violence from her husband in Guatemala. They crossed the border May 19 near San Luis, Arizona, according to the lawsuit, and were immediately approached by Border Patrol agents and taken into custody.

In her lawsuit, she accused US officials of violating her rights when they took away her son days later.

The HHS Administration for Children and Families, which runs shelters that house unaccompanied minors and children separated from their parents, hasn't responded to a request for comment on Mejia's son's case.

The Department of Homeland Security, Immigration and Customs Enforcement and US Customs and Border Protection declined to comment, citing their policy of not discussing pending litigation.

Lawyer: 'This child is not the only child'

Mejia's lawsuit isn't the only one challenging the Trump administration's months-long practice of separating kids and parents at the border, but it appears to be the first filed by an individual since officials announced their controversial "zero tolerance" policy.

On Wednesday a group of detained immigrants filed a similar lawsuit asking a federal court to reunite them with their children. And the ACLU has filed a class action lawsuit over family separations.

In an executive order Wednesday, Trump said he was reversing course and would be moving toward keeping families together in detention rather than splitting them up. But it's unclear how the executive order could affect families who were already separated. Officials with the Department of Health and Human Services (HHS) have said they're awaiting guidance.

On Thursday, members of Mejia's legal team said their fight wasn't over as long as immigrant parents and kids remained separated as a result of the Trump administration's policies.

"This child is not the only child," attorney Mario Williams said. "There's thousands of children similarly situated we have to do something about."

Lawsuit could expand

Mejia was released from custody June 15 after Libre by Nexus, an immigration bond company, paid her $12,500 bond. A legal division of the company is representing her in court.

The bond payment and legal representation are being provided pro bono as part of a program for indigent clients, Nexus Services CEO Mike Donovan says.

Speaking outside the federal court Thursday, Donovan said he hoped to turn Mejia's case into a class-action lawsuit to help other parents reunite with their children.

"It is time to put this very dark and sad and sick and disgusting chapter of American history behind us," he said.

Libre by Nexus has faced accusations of exploiting immigrants and is reportedly under investigation in several states over its practices

Asked about the allegations earlier, Donovan says Mejia's case is just one example of how his company's actions speak louder that any words.

"I care about people. I want mass incarceration in this country to end. And I want incarceration without justification, and incarceration of little kids, especially, to end," he said.

'Nobody is going to separate us again'

Speaking to reporters at the airport early Friday, Mejia said she was happy to have found her son after so many weeks of searching.

"Nobody is going to separate us again," she said.

As smooth jazz played in the background, announcements blared and camera flashes flickered, a reporter asked Mejia if she had any advice for parents in the same situation she faced.

"They can fight the same way I did," Mejia said. "They have to fight to get out of there, to fight for their children."