Long lines and missing packages at the Cornell post office on Lafayette Avenue are leaving Bronx residents frustrated.

Some said they waited more than three hours for packages that never showed up.

The United States Postal Service in a statement explains what could be behind the long lines.

"There are many buildings in the Bronx where property managers have not provided the post office keys to deliver to their building tenants," the statement says. "This means that packages meant for delivery must return to the post office."

The USPS adds that the Cornell post office has added Sunday hours to relieve the lines.