Eshoo said she spoke with detained mothers at the group's second stop, Port Isabel ICE Detention Center in Los Fresnos, Texas, who had not heard if or when they would be able to see their children again.
“[It was] yet another heartbreaker – to hear their stories, how long they’ve been there," Eshoo said. "They don’t know where their children are."
She added that the visit made it clear to her that the federal agencies in charge of the situation don't have a clear plan of how to reunite kids with their families, even after the Trump administration announced Friday that 500 families had been reunited.
"It's very deplorable," added Rep. Lee. "It's sad. There's no due process."
Lee said she believes human rights violations are occurring at the detention facilities.
"I’ve seen it with my eyes, and I’m telling you, I am furious, I am heartbroken, and we’ve got to get this administration to stop this zero tolerance policy,” said Lee, who has called on the United Nations to send humanitarian observers to investigate the situation at the detention facilities.
"I can’t help but think of how ashamed I feel that this is being done in the name of the people of our country,” Eshoo said.
KQED's Tiffany Camhi contributed reporting to this story.