By Jorge Calvillo (staff@latinospost.com) | First Posted: May 31, 2014 02:09 AM EDT

The rise in the number of people illegally crossing the border between Mexico and the United States every day has caused immigration authorities in the United States to take unorthodox measures due to the lack of space in detention centers.

According to Reuters, at least 400 undocumented immigrants, most of them women and children, had to be set free by United States authorities in bus stops around Arizona, since the country's detention centers were at maximum capacity.

According to the same source, American officials said on Thursday that the detention centers for undocumented immigrants which operate in Texas had been overflowing during the last month owing to the rising number of Central Americans who enter the United States through the Río Grande.

"We have enough manpower, this is about detention space," said Andy Adame, spokesman for the United States Border Patrol in Tucson, Arizona.

This measure has not been celebrated by many Republicans in Congress and by border vigilance groups who have said they're worried about 400 people being set free could be seen as an incentive for more immigrants to illegally enter the U.S.

But humanitarian groups in favor of immigrant rights have also criticized the measure since, they say, immigration officials are leaving immigrants in bus stations to their luck, without food, water or any basic supplies.

Cindy Whitmore, volunteer for the Phoenix Restoration Project told The USA Today that on Tuesday night she went to the Greyhound station on Buckeye Road and found 50 women and children who had just been set free by Immigration and Customs Enforcement agents. Among the children were six-month-old babies.

"It's not safe and we're worried about their physical safety. Some of the children were crying, some were babies who were not fully dressed, had no diapers or food," Whitmore told USA Today.

For the moment, in Phoenix and Tucson, volunteer squads have been visiting bus stations to help immigrants with clothes and food and in some cases with buying bus tickets so they can travel to other cities with their family.