Crash closes southbound I-35 near Cassin Road bridge, snarling traffic by Loop 410 interchange

What drivers encountered on I-35

Southbound Interstate 35 near the Cassin Road bridge on San Antonio’s Southwest Side was shut down for hours after a multi-vehicle crash that authorities said began with a stolen car colliding with a small bus hauling a trailer. The closure affected the stretch of highway near the I-35 and Loop 410 interchange, one of the region’s most heavily traveled connectors for commuters and freight traffic.

The crash was reported shortly after mid-afternoon on Thursday, July 17, 2025, and prompted a full shutdown of the southbound main lanes at Cassin Road while first responders worked the scene and investigators documented the collision. The impacted lanes later reopened Thursday evening after being closed for more than five hours.

How the crash unfolded and the human toll

Police said the incident started when the driver of a stolen white Chevrolet Camaro struck a small bus pulling a trailer. The bus then hit a guardrail and was subsequently struck by an 18-wheeler. Authorities said the force of the collision caused the bus to roll onto its passenger side and eject multiple occupants.

Four people were killed. Two died at the scene and two later died at University Hospital. Emergency officials also reported a large number of injuries, including several described as life-threatening, with others transported for treatment of less severe injuries. Authorities said those hurt ranged in age from young children to older adults.

Search for people who fled the scene

Police said multiple individuals left the stolen Camaro and ran from the crash site. Investigators did not immediately confirm how many people fled or whether any were armed, and authorities said those individuals had not been located as of the morning after the crash.

Traffic impacts and what to watch for

Even after lanes reopen following a major collision, drivers can continue to experience residual delays due to vehicle backups, secondary crashes, and ongoing cleanup or investigative activity. In closures near major interchanges such as Loop 410, congestion can spread quickly to feeder roads and alternate routes as traffic diverts.

• Expect stop-and-go conditions near the closure area and on frontage roads during peak periods.
• Watch for sudden slowdowns approaching the interchange and near on-ramps where merging traffic increases.
• Allow extra travel time if routing through the Southwest Side corridor during incident recovery periods.

Drivers approaching major crash scenes are urged to slow down, move over when possible, and follow directions from law enforcement and traffic-control personnel.

The crash remains under investigation, including the circumstances surrounding the stolen vehicle and the identities and actions of those who fled the scene.