Homero Zamorano, 45, was taken into custody in a nearby field after allegedly leaving the 18-wheeler with dozens of migrants hiding in the back in a deserted area of San Antonio on Monday. “He was very high in metatherapy when he was arrested nearby and had to be taken to hospital,” a law enforcement official told the San Antonio Express News. After the gloomy discovery of the bodies inside the truck on Monday night, investigators were able to locate the vehicle at a San Antonio address they were monitoring, authorities said. They later arrested two other men, Juan Claudio D’Luna-Mendez and Juan Francisco D’Luna-Bilbao, when they each left the residence. At least 51 migrants have been killed after being trapped inside a tractor-trailer truck abandoned in San Antonio, Texas on Monday. Getty Images Driver Homero Zamorano, 45, was arrested in a nearby field after allegedly leaving the with dozens of immigrants hidden in the back.REUTERS D’Luna-Bilbao and D’Luna-Mendez were both charged with possession of a firearm while illegally residing in the United States, according to criminal charges. It was not immediately clear what alleged involvement the two men had in the smuggling tragedy or whether they would face additional charges. The driver is also expected to be charged, but has remained in hospital since Tuesday night, a Mexican official said. The death toll rose to at least 51 – including 39 men and 12 women – by Tuesday, authorities said. Two young sisters from Guatemala – Carla and Griselda Carac Tambriz – were also among the victims. Authorities have so far identified at least 27 Mexicans, seven Guatemalans and two Honduras, according to Mexican Foreign Minister Marcelo Ebrad and Mexican Consul Ruben Minutti-Zanatta. The nationality of the other victims has not yet been recognized. A vigil for the dead migrants was held in San Antonio on Tuesday night. REUTERS Sisters Carla and Griselda Carac Tambriz – originally from the cantons of Colcajá, Nahualá, Sololá in Guatemala – have been identified as victims.Twitter / aurabogado Local authorities said they were notified of the tragedy after a city worker heard a cry for help from the back of the truck. Law enforcement arrived to find the back door of the trailer open with “stacks of corpses” inside, while others were scattered nearby. Temperatures in San Antonio reached a high of 103 degrees on Monday. The first to respond found 16 survivors who suffered heatstroke and exhaustion. Survivors treated – including four children – were hot to the touch and dehydrated, according to first responders. With Allie Griffin, MaryAnn Martinez and Post wires