MINNEAPOLIS (WCCO) — Investigators are searching for armed robbers hitting cell-phone stores across the metro.

Eight stores have been robbed this month, seven of them at gunpoint.

Investigators say the robbers have been showing up at closing time and demanding access to the safes.

Employees have been tied up with zip ties and duct tape while the robbers fill bags with phones and tablets.

Security cameras caught a few pictures of the suspects.

Investigators say they typically wear hoodies pulled tight around their faces or Halloween masks.