TUCSON - A sudden onset of triple-digit heat led to a rash of deaths among illegal immigrants over the weekend in Arizona's harsh deserts, with 12 people reported dead between Friday and Monday.
Scores more were saved in nearly 50 rescue operations, U.S. Border Patrol spokesmen said.
The deaths were scattered along Arizona's border with Mexico, but most of the bodies were found in areas west of Tucson, including on the sparsely populated Tohono O'odham Indian Reservation. Three were in far western portions near Yuma, which is at the California line.
The desert areas are the focus of a federal border control initiative, with 200 extra agents brought in for the summer months.
Heat-related deaths have become commonplace in Arizona as migrants have been pushed into remote and harsher terrain by agents cracking down in other border areas. The state is the busiest illegal entry point on the nation's southern border.
In the fiscal year that ended Sept. 30, 55 immigrants died in Arizona because of the heat, according to the Border Patrol. A total of 172 illegal immigrant deaths were recorded during the same period.
Advocates and border enforcement officials say immigrants are often unprepared for the extreme heat or unaware of the conditions and long hikes they'll face once they cross into Arizona.
Over the weekend, Border Patrol search-and-rescue agents in the agency's Yuma office conducted a dozen rescues. Search-and-rescue supervisor Dan Sprick called it his team's busiest three-day period ever as they found 40 people stranded in the desert.
Seven people were treated for heat illnesses but all declined further medical treatment, Sprick said.
Another 37 rescues were conducted in the Tucson sector, which covers all but the westernmost part Arizona's border with Mexico. Agents who responded to a cell phone call for help found 23 people in one rescue alone.
The body count began with a man in his early 20s was found Friday evening near Nogales. It continued with others found sporadically on Saturday, Sunday and Monday.
All but the last body discovered were tentatively listed as heat-related deaths, pending medical autopsies, Tucson sector spokesman Luis Garza said. The 12th body, found Monday, was likely in the desert for several weeks, officials said.
Rescued migrants repeatedly told Border Patrol agents that their smugglers, also known as coyotes, had instructed them to "only grab a gallon or two of water. They never said anything about walking for two or three days," Garza said.
"What scares me is that there just continues to be very widely scattered deaths," said the Rev. Robin Hoover, founder of Humane Borders, a Tucson-based organization that puts out jugs of water in areas of the desert used heavily by illegal immigrants.
"It doesn't appear that law enforcement has sealed off even one of the corridors coming into the United States. So it's business as usual, as it's been for five years for us."
Hoover and Jennifer Allen, director of Border Action Network, another immigrant advocacy group, said they were hopeful that guest worker legislation could make its way through Congress.
"It won't come into effect quick enough" to help people trying to cross the deadly deserts now, Allen said.
Added Hoover: "We're still here for the long haul, and it doesn't look good," Hoover said. "It looks bleak."