Federal investigators are examining why an Amazon cargo jet barreled off a runway at Miami International Airport and into vehicles, killing at least five people. The focus is likely to center on a crucial moment in the landing: whether the plane touched down too late to stop safely.

Video of Sunday’s landing appears to show the aircraft touching down well down the runway before overrunning it. The incident occurred at Miami International Airport, one of the busiest in the United States.

The National Transportation Safety Board is leading the probe into the crash. Investigators will review flight data, cockpit voice recordings, and runway conditions as part of their work.

Amazon operates a large fleet of cargo aircraft that deliver packages across the country. The company has faced scrutiny in the past over operational safety at its facilities.

Authorities have not released the identities of the victims. The crash disrupted operations at the airport for several hours on Sunday.

Weather conditions at the time of the landing were reported as clear. No other aircraft were involved in the incident.