Police near San Antonio report that 48 migrants are dead and at least 16 others were transported to local hospitals after being locked inside a tractor-trailer. Two more died after receiving medical care. A worker found the tractor-trailer on the southwest side of San Antonio on a back road near Interstate 35. Police say the driver may have been involved in a human smuggling incident.

UPDATE: By Wednesday, the death toll climbed to 53 migrants, officials reported. Two men are charged in relation to the deaths of the migrants, USAToday reported.

Original story follows:

A senior law enforcement source on the scene told Breitbart Texas that 46 migrants were declared dead on the scene or at area hospitals and at least 16 others were taken to area hospitals. The dead-on-scene figure was later revised to 48. A source on the scene says they have a person of interest in custody. That person was also reportedly transported to an area hospital. At least 60 migrants were packed inside the trailer.

Among the dead were teenage migrants, KSAT reported. It is not known if they were accompanied or not. Four minors survived and were taken to area hospitals, officials reported in a Monday night press conference.

Due to the circumstances, ICE Homeland Security Investigations special agents were called in and are taking charge of the investigation. Border Patrol agents are also reported to be on the scene.

The law enforcement source told Breitbart the person of interest may have attempted to blend in with the migrants and was transported to a hospital. San Antonio Police Chief William McManus told reporters there are three people in custody in connection to the deaths. He did not indicate what their connection to the incident is, KXAN reported.

Chief McManus said a worker heard cries for help coming from inside the trailer. The worker opened the partially opened door and observed dead migrants inside.

Breitbart Texas reports extensively on the practice of human smugglers moving migrants in tractor-trailers.

Earlier this month, local police agents found two migrants dead in a tractor-trailer loaded with 111 migrants, Breitbart Texas reported. La Salle County Sheriff’s deputies responded to frantic 911 calls from migrants being smuggled in a semi-tractor trailer near Encinal, Texas, on Friday. Dispatchers could hear screams from migrants trapped inside the closed trailer traveling north and away from the border on Interstate 35. When the vehicle was encountered, two migrants were dead and 111 were apprehended after an exhaustive search.

Breitbart Texas reached out to HSI officials for additional information. A response was not available at press time. Officials did say they would be sending a statement shortly. This article will be updated at that time.

Nearly five years ago, San Antonio police found another tractor-trailer where eight migrants were dead and 20 others were listed in critical or serious condition.

Bob Price serves as associate editor and senior news contributor for the Breitbart Texas-Border team. He is an original member of the Breitbart Texas team. Price is a regular panelist on Fox 26 Houston’s What’s Your Point? Sunday-morning talk show. Follow him on Twitter @BobPriceBBTX and Facebook.

Randy Clark is a 32-year veteran of the United States Border Patrol.  Prior to his retirement, he served as the Division Chief for Law Enforcement Operations, directing operations for nine Border Patrol Stations within the Del Rio, Texas, Sector. Follow him on Twitter @RandyClarkBBTX.

Editor’s Note: This is a developing story and will be updated as additional information becomes available. This article has been updated to reflect the latest information regarding the number of deaths and survivors.