What hazard made the evacuation of passengers from the Delta flight at Toronto International Airport so urgent?

The evacuation was urgent due to leaking jet fuel, which created multiple dangers at the crash site. The fuel was described as 'highly flammable' and 'very dangerous,' posing an immediate fire risk. Additionally, the fuel vapors could be poisonous if breathed in for extended periods, creating a secondary health hazard for trapped passengers. CBS correspondent Tom Hansen emphasized that getting people out of the aircraft quickly was 'paramount in saving lives' given these conditions. First responders prioritized swift evacuation to remove all 80 passengers from harm's way before the leaked fuel could ignite or cause respiratory issues.