TULSA, Oklahoma - The post office has launched an investigation after an outside collection box at a south Tulsa post office was vandalized early Friday.

The box is located outside the post office in the 6900 block of South Yorktown. The post office won't confirm if any mail was stolen from the box.  

The Postal Service says customers should not put mail in an outside collection box after the final pickup time listed in the box, because the box is unattended overnight.

Inspectors say if customers believe their mail was stolen, they should submit an online complaint or call 877-876-2455.