Two propane-delivery trucks were found June 2 just outside Laredo, TX, after being stolen from a gas company over the weekend, The Associated Press reported.

San Antonio Police spokeswoman Sandy Gutierrez said she did not know whether the trucks were still carrying the fuel.

Police Chief Albert Ortiz said June 1 that his department did not suspect terrorism was behind the thefts. But officials said that since September 11, such a possibility couldn’t be ignored.

"Four years ago, we probably would not be too concerned about this,” San Antonio FBI agent Patrick Patterson said Wednesday on NBC's "Today." "It would be a major theft and handled like any other criminal investigation. Because of the nature of the day, we are very, very concerned about the whereabouts of these two trucks."