Surveillance video shows a bus driver ignoring flashing lights as he maneuvers around a partially lowered railroad crossing barrier in Buenos Aires.
The crash killed 11 people, including the bus driver. More than 200 people suffered injuries.
Investigators acknowledge the bus driver ignored the signals but they say earlier in the day, a garbage truck broke off the end of the wooden barrier.
The recording shows a garbage truck breaking the end of the wooden, red-and-white painted barrier hours before Tuesday's pre-dawn crash. It then shows a security guard waving drivers across despite signals warning of nearby trains.
The video also shows that the security guard left just minutes before the 6:23 a.m. accident, and that someone had stuck a pole in the barrier to keep it from blocking traffic. It then shows a flow of traffic driving under the partially lowered barrier moments before the bus driver gambled that he could make it across as well.
The Associated Press contributed to this report.