Five people in Texas have been charged with participating in an alleged smuggling operation after 97 migrants were found in a single Houston home.
The discovery on Friday by Texas police shocked the community which is more than 300 miles (480km) from the nearest border crossing with Mexico.
All five of those charged are in the US illegally, according to US officials.
It comes after the month of March saw the most border crossings in 20 years and a surge of children arriving.
In a statement, acting US Attorney Jennifer Lowery said the suspects are all accused of "harbouring, concealing and shielding illegal aliens for the purpose of commercial advantage or private financial gain".
The suspects include one person from Honduras, two from El Salvador and two from Mexico, officials say. They each face 10 years in jail if found guilty.
All of the people found in the home - which is referred to in court documents as a "stash house" - were men, except for five women. All were adults.
They were all found in two bedrooms that were allegedly bolted from the outside in order to prevent escape.
The men were all found in their underwear. Some were taken to hospital after telling police they had not had any food or water in three days.
So far five of them have tested positive for Covid-19, according to the Houston Health Department. More test results are pending.
Officials say the investigation began after a woman called authorities to say that her brother had been kidnapped.
The woman had already paid $11,000 (£8,000) to get her brother to the US, but the smugglers were threatening to kill her if she did not pay more, police say.
After police tracked a suspect's phone to the home, a raid was carried out by the Houston Swat team.
According to investigators, one person in the home was allegedly told that if they did not pay, they would be put in "four pieces of wood", meaning a coffin.
A ledger containing names and sums paid was also found in the rental home. Officials say they do not know how long the rental home had been used for the alleged crimes.
The homeowner told KTRK-TV that she had no idea what the home was being used for.
"It's really strange that so many people can be inside a house, and we didn't notice," neighbour Kai Lynch told the Houston Chronicle newspaper. "We really need to be more vigilant."
The raid on Friday came after several other alleged stash houses were uncovered by officials earlier that week.
On Wednesday, Border Patrol agents raided four homes in the Rio Grande Valley and discovered 52 undocumented immigrants.
On Thursday, 27 undocumented immigrants were found in another home in Edinburg, Texas.