Chief Jeff Bert of Tomball Police said the incident happened at around 1:15 p.m. Nov. 3 when a man with the package walked into a T-Mobile store in the area of Business 249 and FM 2920.
According to the chief, the man was angered during a confrontation around that time. He then hit a button on a device with a blinking light, which prompted police to be called.
The Harris County Bomb Squad was brought in, and a robot was used to X-ray the device and then detonate it outside the business.
Police detained one person in the aftermath of the emergency.
It is not immediately known if the device contained explosives.
The nearby intersection was reopened around 4:45 p.m.
Given the timing of the call, police emphasized to Community Impact Newspaper's partners at ABC13 that the shopping center did not contain a polling location.
A search of Harris County voting centers showed Tomball Intermediate School, located about a mile away, as the closest.
This is a developing story. Find the latest updates at ABC 13.