"Avoid the NYS Thruway eastbound at all costs as a tour bus has rolled over near the Erie and Genesee County lines," Erie County executive Mark Poloncarz said on X. "This is a potential mass casualty incident," he said, adding that the county's emergency and security services are assisting.

A tour bus carrying 54 people was traveling back from Niagara Falls to New York City when the bus lost control and crashed into a ditch about 30 miles outside Buffalo. NBC’s Sam Brock reports.