Cleveland residents are concerned with the police building up in the city.
The alarm is given in anticipation of a verdict for police officer Michael Brelo that is to take place on May 18 or 19.
Brelo was accused of voluntary manslaughter for shooting two unarmed black suspects. Timothy Russell and Malissa Williams were both gunned down in a barrage of 137 shots fired by 13 Cleveland officers.
National Guard company was ordered to report to home station on May 17 with 72-hour bags.
Clevelend residents evidenced "police driving around with riot shields sticking out of their trunks" as well as a train transporting military vehicles.
"A girl on Facebook posted a photo of the riot gear her father received from the Cleveland Police Dept.," a Cleveland resident tweeted. "It truly amazes me that Cleveland is armed for a riot that hasn't even started yet."
Area police departments were reported to purchase riot gear, bulletproof vests and other safety equipment.
Hank Davis, a former gang member who now works with at-risk youth, heard that out-of-town agitators have already arrived in Cleveland and are pressuring residents to riot after the verdict.
Also read: Why American police incite riots