It happened shortly after 10 p.m.
According to police, an 84-year-old man hit the gas instead of the breaks.
No one was hurt.
The post office stayed opened, but access to some P.O. boxes required help from employees.
Those whose P.O. boxes are cordoned off will have to go in during normal 9-5 business hours to get help from the staff.
The driver wasn’t cited, but Medford Police is requesting the driver be re-tested at the Department of Motor Vehicles.