U.S. Border Patrol stepped up heatwave warnings in the southwest of the country for migrants trying to cross the border from the Sonoran Desert, it was reported Sunday.

Authorities warned of an intensifying heatwave across the southwestern states and its potential jeopardy on the elderly, the infirm, the homeless, as well as migrants looking to cross the border into the U.S.

The National Weather Service said temperatures in Phoenix, Arizona, could peak at nearly 49 Degrees Celsius (120 Degrees Fahrenheit) by Tuesday and an excessive heat warning is to remain in effect until Thursday, The Guardian reported.

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The U.S. Border Patrol’s division in Yuma said it had put its search, trauma, and rescue team on a high alert for migrants struggling to survive in the desert. “It is physically impossible for the average person to carry enough water to survive several days of walking through the desert,” an agency statement said.

Just after that statement was issued, border patrol agents were reported to have raided a medical center Thursday and detained four people near the town of Arivaca.

The move was criticized by activists as something that put lives at risk. The raid was conducted on a humanitarian aid camp run by the No More Deaths group around 60 miles to the south of Tuscon and 15 miles from the border.

President Donald Trump’s hard stance on immigration was cited as a reason for the breaking of a supposedly longstanding agreement where border agents were expected to not interfere with the medical facility and view it as a camp under international Red Cross standards.

“People crossing the deadly and remote regions of the US-Mexico border often avoid seeking urgent medical care for fear of deportation and incarceration. For this reason, a humanitarian-focused aid station in the desert is an essential tool for preserving life,” read a statement from the group. "The targeting of this critical medical aid is a shameful reflection of the current administration’s disregard for the lives of migrants and refugees, making an already dangerous journey even more deadly," the statement added.

Meanwhile, if the heatwave gets up to the 120 Fahrenheit mark, it could match the record set on July 28, 1995, for the hottest day in the history of Phoenix.

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Other parts of the southwest are also expected to continue experiencing what has been called a triple-digit heat wave. Furnace Creek in California saw a high of 119 degrees while Blue Water in Arizona got up to 113 degrees. Midland in Texas meanwhile was at 112 degrees, CBS News reported.

The conditions were reportedly making it difficult for crews tackling wildfires. Excessive heat warnings were issued in parts of Utah and Arizona, even extending to Nevada. A number of wildfires in Arizona even led to six firefighters needing treatment for heat-related illness. They were fighting a highland fire in Payson.

Monday is expected to witness the hottest temperatures in the southwest and the heatwave is expected to go on till the end of next week. Death Valley in the southern California Desert is expected to see a high of 127 Degrees Fahrenheit.

At the same time, air quality was another issue cited as a cause for concern. Heat-induced ozone pollution was expected to reach unhealthy to very unhealthy levels in a number of inland communities.