A tractor-trailer found near Lackland Air Force Base in San Antonio contained the bodies of 46 dead people, along with 16 others who have been taken to hospitals, local officials in San Antonio said on Monday evening.

The horrifying discovery was made near the intersection of Cassin Drive and Quintana Road in Southwest San Antonio, according to a local official who spoke to The Texas Tribune on condition of anonymity. The official said that Mayor Ron Nirenberg and Police Chief William McManus would give a briefing to the press at 9 p.m. near the site of the discovery.

The official said that federal, state and local authorities believed that the bodies were those of migrants. Cross-border smuggling and human trafficking have been longstanding problems along the U.S.-Mexico border, but the deaths of 46 people represent a stunning loss of life.

KSAT-TV reported that ambulances and law enforcement officials, including agents from the U.S. Customs and Border Protection, had swarmed the scene.

This is a developing story; check back for details.

This article originally appeared in The Texas Tribune, a member-supported, nonpartisan newsroom informing and engaging Texans on state politics and policy. Learn more at texastribune.org.

Jaden Edison is a 2022 summer reporting fellow for The Texas Tribune.