Law-enforcement officials move around a vehicle stopped on a section of I-75 in south Florida called "Alligator Alley." _
MIAMI, Florida (CNN) -- Authorities closed a major east-west highway, known as "Alligator Alley," in south Florida early Friday and established a no-fly zone above the area after stopping suspects who could be plotting a terror attack in Miami, law enforcement sources told CNN.
The 80-mile section of Interstate 75 was closed after a Collier County Sheriff's deputy pulled over a vehicle around 1 a.m. ET matching a description issued on an earlier alert, according to Collier County Sheriff's spokeswoman Tina Osceola.
A second vehicle pulled in behind the suspected vehicle -- about eight miles east of the western toll booth -- and the deputy called for backup, Osceola said. A bomb-sniffing dog responded to both vehicles, and the people in the cars were detained by Collier County Sheriff department.
Osceola said three suspects were being detained.
Florida law enforcement officials issued an alert Thursday night after a Georgia woman overheard a conversation among three men in a Calhoun, Georgia, restaurant. She said the conversation indicated they were planning a September 13 terror attack on Miami, according to a report by Miami's WSVN-TV.
The men then left the restaurant and headed south on Interstate 75, the report said.
Alligator Alley is a major cross-Florida highway that runs between Naples on the west to near Fort Lauderdale on the east.
