(CNN) The number of undocumented immigrants being released by federal authorities in Rio Grande Valley in Texas is soaring.
As of Friday, about 2,000 immigrants had been released by US Customs and Border Protection into three cities in the area: McAllen, Brownsville and Harlingen.
With several facilities in the Rio Grande Valley over capacity, cities are preparing to handle thousands more migrants who will be moving through the area before starting the trek to other destinations.
Brownsville City Manager Noel Bernal said Saturday that while initially only around 50 people were being dropped off on a daily basis, the number had averaged around 300 more recently with more expected to be released in the coming days.
Customs and Border Protection has been saying for months that "the immigration system is broken and that they are at critical capacity levels across the southwest border. CBP's facilities and manpower cannot support this dramatic increase in apprehensions of family units and unaccompanied children."
About 1,000 undocumented immigrants are being apprehended each day in the Rio Grande Valley sector, a customs spokesperson said. CBP told CNN it was working to determine how many people will be released in coming days.
The Border Protection facility in Brownsville, according to a tweet from the agency, is at 174% capacity with 5,355 people in custody.
So far, Brownsville hasn't had any migrants stay more than one night, Bernal said.
"Our focus has been not to become a permanent stop but just to be a temporary stop where we are a conduit to facilitate their journey," Bernal said.
CBP has released undocumented immigrants into the area before, under the Obama administration, but the situation was more coordinated then, he said.
"It's a different administration and it's a different environment," Bernal said.
In the past, Border Protection has given released migrants a ticket to a new town.
But Bernal said city staff and nonprofits are doing more hands-on work to provide cell phones to the migrants, help them contact families and purchase tickets to travel to relatives.
According to an email from the CBP to Rio Grande Valley cities, there is a tentative plan to construct a "soft-sided" facility near the Donna Port of Entry, in Donna, Texas.
In the meantime, Texas shelters along the border have scrambled to house migrants. Last week, the Border Patrol in the Rio Grande Valley began releasing people directly from its custody with a notice to appear in court -- something that had not been done since 1998, according to a Department of Homeland Security official.
The agency is prioritizing female-head-of-household families for release. Unaccompanied children are also a priority, but they are transferred to custody of Health and Human Services.
Federal authorities want help from legislators.
"DHS is committed to addressing this humanitarian need, but the current situation is unsustainable for Border Patrol operations," the Border Protection statement said. "This status quo is not an option. The legal framework must be addressed. The only remedy to this crisis is congressional action."
President Donald Trump weighed in on Twitter on Saturday, blaming Democrats and saying the fix would take an hour and a vote. "But the Dems don't care about the crime, they don't want any victory for Trump and the Republicans, even if good for USA!" he wrote.
He added another tweet saying Mexico must stop people trying to go through the country and into the United States.
"Our detention areas are maxed out & we will take no more illegals. Next step is to close the Border! This will also help us with stopping the Drug flow from Mexico!" he said, following up on his statement Friday in which he said he would take action next week.