Border crossings closed after vehicle explosion on bridge connecting New York and Canada

US terrorism investigators deployed Wednesday after a car erupted into a fireball at a US-Canada checkpoint, triggering border closures on one of the busiest travel days in the American holiday calendar

Two people were killed in the blast, according to US media citing authorities, although their identities were not yet public.

The car exploded at the major Rainbow Bridge crossing near Niagara Falls, local and state authorities said.