Forty-six persons were found dead inside an abandoned tractor-trailer on Monday in San Antonio city of Texas in the United States, the Associated Press reported. The dead are believed to be migrants who had crossed over to the US from Mexico, according to the New York Times.

Sixteen more persons, including four children, have been hospitalised.

An employee of the city’s civic authorities discovered the bodies around 6 pm on Monday local time, after he heard someone crying for help, local police chief William McManus said.

Those taken to the hospital were dehydrated and their bodies were hot to touch, Fire Department chief Charles Hood told AP. He added that no water was found on the trailer.

The home countries of the immigrants have not been confirmed yet, and the authorities do not know for how long they had been abandoned on the road.

Meanwhile, the US Homeland Security Investigations has started an inquiry to find out whether the incident was a result of an attempt to smuggle migrants into the the country, McManus said. Three persons have been taken into custody, but it was not clear if they were involved with human trafficking, the police chief added.

San Antonio Mayor Ron Nirenberg said that those who died had “families who were likely trying to find a better life.”

“This is nothing short of a horrific human tragedy,” Nirenberg said.

The southern part of Texas is a route often used for illegal border crossings, AP reported. Migrants use San Antonio, the closest major city to the Mexico border, as a point to disperse to various parts of the US.

Ten migrants had died in 2017 after being trapped inside a truck that was parked at a Walmart store in San Antonio. In 2003, 19 migrants were found in a sweltering truck near San Antonio.