The fuel company "pulled the plug. When that happens, you can't put the plane in the air," said spokesman Ed Warneck.
The regional airline, which is in Myrtle Beach, S.C., suddenly canceled all flights, just when many families were packed and ready for vacation trips south, The Buffalo (N.Y.) News reported Wednesday.
Travelers scrambled for alternative plans, finding themselves renting cars or paying for new arrangements with another airline.
A party of 20, members of the Colucci and Coia families of western New York, were headed from Niagara Airport to Disney World. They ended up switching to Spirit Airlines, which meant landing in Fort Lauderdale, Fla., instead of Lakeland airport near Orlando.
That meant renting a car, a connecting drive to Orlando and an extra $1,000 added to their trip, they said.
On its Web site, Direct Air said on it was closing down until May 15, "to address operational matters."