Local Terror Expert: "If We Become Scared, The Terrorists Are Winning"

DALLAS (CBSDFW.COM) - Americans have watched terrorist attacks involving trucks play out overseas in countries like France. But on Tuesday, a similar attack happened on U.S. soil after a vehicle was used as a weapon for terrorism.

Investigators believe Sayfullo Saipov rented a truck and purposely drove into a crowd of people with the intent to kill.

"It's kind of nonchalant as far as any type of threat is concerned…until that threat becomes actual actions," said Danny Defenbaugh, a former FBI Special Agent.

Defenbaugh spent decades with the FBI and lead investigations during terrorist attacks like the Oklahoma City Bombing.

"There is no text book," said Defenbaugh.

He said the use of a vehicle only makes the investigation more complicated.

"How'd he rent that truck? What were his statements? What did he say? Was he with someone else?" questioned Defenbaugh.

He expects investigators to search for what motivated the 29-year-old suspect and who worked with him, if anyone at all.

"There's a lot of different pieces to that puzzle that will have to be put together rather quickly," said Defenbaugh.

What mystifies him, the truck driver is from Uzbekistan. Defenbaugh said it is not a country typically "on the radar" of those within the intelligence community. "It opens up so many doors and avenues that haven't been touched or related to," he said.