URBANDALE, Iowa -- Pipe bombs accompanied by anti-government propaganda exploded Friday in six mailboxes in rural parts of Illinois and Iowa, injuring six people in an attack authorities called domestic terrorism.
Two other bombs were found but did not detonate, and a note found with them said more "attention getters" were on the way. It was signed "someone who cares."
Authorities did not immediately announce any suspects. The Postal Service suspended deliveries through Saturday in the agricultural region that straddles the Mississippi River, and urged residents not to remove any devices they might find in their mailboxes.
"We are reviewing this as a domestic terrorism incident," said James Bogner, an FBI spokesman. "We don't know if all the devices have been found or there are devices remaining ... We probably won't know for a while."
In all, eight devices were found and six exploded. The bombs were not sent by mail but were instead placed in the mailboxes and set to detonate when the boxes were opened, investigators said.
Postal Service Inspector Linda Jensen said consistencies in placement suggested the bombs were linked, but that did not mean just one person was involved. All the communities can be reached within a day's drive.
None of the injuries was considered life threatening, but Carroll County, Ill., Sheriff Rod Herrick warned residents against opening their mailboxes.
Postal Service vice president Azeezaly Jaffer said the bombs were accompanied by a typewritten note that began: "Mailboxes are exploding! Why, you ask?"
Then it said, in part:
"If the government controls what you want to do they control what you can do. ... I'm obtaining your attention in the only way I can. More info is on its way. More 'attention getters' are on the way."
The bombs appeared to be triggered by being touched or moved. Jensen described the devices as three-quarter inch steel pipes with a 9-volt battery attached. Accompanying the bomb was a clear plastic bag containing the note.
Chicago FBI officials said their Joint Terrorist Task Force would help in the investigation. Federal officials did not say how many investigators would be involved.