WESLACO, Texas — Eighty-four undocumented migrants were rescued from a tractor-trailer Thursday in South Texas, according to Hidalgo County Sherriff Eddie Guerra.

According to a tweet by Guerra, a concerned citizen called to report the semi-truck parked in a residential area in Weslaco, Texas.

Deputies with Homeland Security's Operation Stonegarden program and U.S. Border Patrol responded to the scene and rescued the migrants. An investigation is ongoing.

According to CNN, most of the migrants are from Central America and none of them asked for medical assistance when they were found. Agents with ICE Homeland Security Investigations are looking into the incident as a possible case of human smuggling.

This incident is not the first of its kind this year. In late June, 53 migrants were found dead from heat and dehydration inside an abandoned and locked truck trailer just outside of San Antonio. The migrants came from Mexico, Honduras and Guatemala. Some of the bodies of the migrants were flown back to their home countries to be buried.

In 2017, 10 people were found dead inside a truck outside a San Antonio Walmart. In 2003, 19 migrants were found dead in another hot truck just southeast of the city.​