LITTLE ROCK, Ark. -- The FBI wants law officers assigned to areas around the Mississippi River bridges at Memphis, Tennessee, to keep an eye on the spans after a vague threat that one would be blown up.
FBI spokesmen said Tuesday the threat was unsubstantiated but that local police were still notified.
Two cross-country routes traverse the Mississippi River at Memphis -- Interstates 40 and 55. They remained open. The FBI said Tuesday it notified police of "potential danger" from an Islamic State cell in Memphis and that both bridges needed to be monitored.
Highway officials reviewed plans for rerouting traffic.
The Arkansas Department of Emergency Management said the threat had not reached a level requiring it to put anyone on stand-by. Spokesman Rick Fahr said threats that include specifics are rare.