Migrant families from Mexico and Central America desperately searched for news of their loved ones as authorities began work Tuesday to identify 51 people who died after being abandoned in an air-conditioned semi in sweltering Texas heat.This is the tragedy with the highest number of fatalities during a migrant smuggling operation from Mexico.The truck driver and two other people were arrested, Texas US Rep. Henry Cuellar told The Associated Press.He reported that the vehicle had passed through a Border Patrol checkpoint northeast of Laredo, Texas, on Interstate 35. He did not know if there were any migrants inside the truck when it passed through the checkpoint.Investigators traced the truck's registration to a residence in San Antonio and arrested two men originally from Mexico for weapons possession, according to criminal complaints filed by federal prosecutors.The complaints do not make any specific accusations related to the deaths.The bodies were discovered Monday afternoon outside San Antonio when a city employee heard a cry for help from the truck parked on a lonely back road and found the gruesome scene inside, Police Chief William McManus said.Hours later, the body bags could be seen on the ground of the place.More than a dozen people, whose bodies were extremely hot, were taken to hospitals, including four children.Most of the victims were male, he said.The death toll is the highest ever recorded in a human trafficking incident in the United States, according to Craig Larrabee, acting special agent with Homeland Security Investigations in San Antonio.“This is a horror that surpasses anything we have ever experienced before,” San Antonio Mayor Ron Nirenberg lamented."And sadly it was a preventable tragedy."President Joe Biden called the deaths in Texas "gruesome and heartbreaking."“Exploiting vulnerable individuals for money is shameful, as is the politics associated with any tragedy, and my administration will continue to do all it can to prevent smugglers and traffickers from preying on people trying to enter the United States between ports. input,” Biden said in a statement.The authorities did not know the countries of origin of all the migrants and how long they had been abandoned on the road.As of Tuesday afternoon, medical examiners had potentially identified 34 of the victims but were taking other steps, such as fingerprints, to confirm their identities, Bexar County Commissioner Rebeca Clay-Flores said.Twenty-seven of the dead are believed to be of Mexican origin because of the documents they were carrying, according to Ruben Minutti, Mexico's consul general in San Antonio.Several survivors were in critical condition, with injuries including brain damage and internal bleeding, he added.At least another seven were Guatemalan and two Honduran, tweeted Roberto Velasco Álvarez, head of the North American Unit of the Mexican Ministry of Foreign Affairs.About 30 people contacted the Mexican consulate looking for their loved ones, officials said.Authorities confirmed that one of the surviving Mexicans is José Luis Guzmán Vázquez, 32, from San Miguel Huautla, in the state of Oaxaca, according to Aida Ruiz García, director of the Oaxacan Migrant Assistance Institute.Guzmán suffered from dehydration and is being treated at a San Antonio hospital, the Mexican Ministry of Foreign Affairs reported.A cousin, Alejandro López, said his family worked in agriculture and construction and migrated out of necessity.Attempts to cross the border from Mexico into the United States have claimed thousands of lives in both countries in recent decades.US border authorities are apprehending migrants at the southern border more frequently than at any time in at least two decades.There were nearly 240,000 migrant apprehensions in May, a third more than a year ago.Comparisons with pre-pandemic levels are tricky because migrants removed from the United States under a public health order known as Title 42 face no legal consequences, encouraging repeat attempts.Authorities say that 25% of the encounters in May were with people who had already been detained at least once in the previous year.South Texas has long been the busiest area for illegal border crossings.US authorities discover trucks with migrants inside “almost daily,” Larrabee said.Migrants typically pay between $8,000 and $10,000 to be driven across the border, loaded onto a truck and taken to San Antonio, where they are transferred to smaller vehicles for their final destinations in various parts of the United States, he said. the.Conditions vary widely, including how much water passengers receive and whether they are allowed to carry mobile phones, Larrabee said.Authorities believe the truck discovered Monday had mechanical problems when it was left alongside a railroad track in an area of ​​San Antonio surrounded by junkyards near a busy highway, said Nelson Wolff, a Bexar County judge and top public official. local."They just parked it on the side of the road," he said.In recent years, San Antonio has been a recurring scene of tragedies related to migrants in cargo trucks.Ten migrants died in 2017 after becoming trapped inside a truck parked at a San Antonio Walmart.In 2003, the bodies of 19 migrants were found in a truck southeast of the city.More than 50 migrants were found alive in a trailer in 2018, driven by a man who said he would be paid $3,000 and was sentenced to more than five years in prison.Other tragic incidents have occurred long before the migrants reach the border.In December, more than 50 died when a truck carrying them overturned on a highway in southern Mexico.In October, Mexican authorities reported discovering 652 migrants in six trucks near the border.They were detained at a military checkpoint.Those people who were taken to hospitals were hot to the touch and dehydrated.No water was found inside the trailer, Fire Chief Charles Hood said."They were suffering from heat stroke and fatigue," Hood said."It was a refrigerated tractor trailer, but no working air conditioning unit could be found inside that trailer."Temperatures in San Antonio on Monday hovered around 100 degrees Fahrenheit (38 degrees Celsius).Tractor-trailers became a popular method of smuggling in the early 1990s following increased border enforcement in San Diego and El Paso, Texas.Before then, people paid a small fee to smaller operators, usually a couple, to take them across a barely guarded border.After crossings became exponentially more complicated following the 2001 terrorist attacks, migrants moved through more dangerous terrain and had to fork out thousands of additional dollars.Some activists linked the incident to the border measures of the Biden administration.Aaron Reichlin-Melnick, policy director at the American Immigration Council, wrote that he had feared a tragedy of this magnitude for months."With the border as closed as it is today to migrants from Mexico, Guatemala, Honduras and El Salvador, people have been forced to take increasingly dangerous routes," he wrote on Twitter.During a vigil in the rain Tuesday afternoon at a San Antonio park, many of the more than 50 present expressed sadness, frustration and anger over the deaths and what they described as a broken immigration system.“I saw this happen, and it was something that didn't have to happen.If there was a better way for Hispanic and Black people to get in safely, they wouldn't have to go through these desperate measures,” said San Antonio resident Debbie Ponce.There have been more than 2 million expulsions of migrants — mainly from Mexico, Guatemala, Honduras and El Salvador — under a pandemic-related rule in place since March 2020 that denies them the ability to apply for asylum.The Biden administration planned to end the policy, but a federal judge in Louisiana blocked its attempt in May.U.S. Customs and Border Protection reported 557 deaths at the southwest border in a 12-month period ending Sept. 30, more than double the 247 recorded in the previous year and the highest number since the US began. records in 1998. Most deaths were related to heat exposure.Spagat reported from San Diego.Associated Press writers Eric Gay in San Antonio, Acacia Coronado in Austin, Ken Miller in Oklahoma City and Terry Wallace in Dallas contributed to this report.