Police, along with federal postal inspectors, are investigating a burglary at a Michigan City-area post office facility used daily to deliver hundreds of pieces of mail.
Michigan City postmaster Tracy Cioch said Monday it's not known yet if any mail or what else might have been taken.
"I know postal inspectors are working on it," Cioch said.
According to LaPorte County Sheriff's Department, officers about 9 a.m. Saturday were called to Weatherstone Village, a community along U.S. 20 just west of Michigan City.
Investigators believe the burglar tried first to kick open the door judging by a muddy footprint left on a door found open on the United States Postal Service-owned building.
The lock on the door had also been pried off, authorities said.
A 6-inch long hunting style knife used to pry off the lock was recovered from inside the building.
Postal workers were called to the scene and after going through the building told investigators "nothing appeared to be out of the ordinary," investigators said.
A man walking his dog before sunrise told police he heard noises from inside the structure but didn't notice the open door until daybreak.
Cioch said the building contains built-in mailboxes for residents of the park and is used strictly by postal carriers to go inside and deposit the mail.
Residents of the community from the outside retrieve their mail by sliding the boxes in and out.
Cioch said the supplies are not kept in the building, which is manned only when postal carriers stop to deliver mail on their route.