NAPLES, FL. Authorities have shut down Interstate 75, the main east-west route across the Florida Everglades as they investigate a possible terrorist threat.

Also known as Alligator Alley, the road was closed early this morning after three people in two vehicles were detained. According to the Associated Press, E.J. Picolo of the Florida Dept. of Law Enforcement reported that bomb-sniffing dogs alerted authorities to material in both vehicles.

The Florida Highway Patrol sealed off a 20-mile stretch of the highway shortly after 1 a.m. today when the suspicious vehicles were stopped.

Alligator Alley is the main route from Naples to Fort Lauderdale in South Florida. The Florida Highway Patrol said I-75 was closed from a toll booth east of Naples to State Road 29.