Ohiowa, Neb. ? Rural carriers planned to deliver mail as usual on Monday despite the discovery of six mailbox pipe bombs in Nebraska that brought to 14 the total number of the weapons found across the Midwest in recent days, authorities said Sunday.

No arrests had been made in the case Sunday, as officials renewed pleas that whoever planted the bombs contact them and make their grievances clear.

“I hope whoever is responsible would respond,” said Thayer County Sheriff David Lee, whose department received a call on one bomb found in a rural mailbox near Davenport on Saturday.

Six people were injured by explosions in Illinois and Iowa on Friday. None of the six bombs found Saturday in rural areas of Nebraska went off. They were later detonated harmlessly by authorities.

An anti-government note found with the bombs warned of more “attention getters,” and federal authorities described the bombs as an act of domestic terrorism.

“We’re still trying to get this thing put together. We are aggressively investigating,” said FBI spokesman Pete Sakaris in Omaha.

Among the six people injured Friday, only a 61-year-old woman remained hospitalized Sunday. Doris Zimmerman, who lives near Anamosa, Iowa, was listed in fair condition.

No widespread inspections of rural Nebraska mailboxes were planned, and rural carriers intended to deliver mail as usual Monday, said Dave Margritz, a postal inspector in Omaha.

Rural carriers will be on heightened alert, Margritz said Sunday.

Mail carrier Lyle Bartels of Ohiowa said he’ll be cautious when he returns to his route. Two of the pipe bombs found Saturday were in his delivery area.

“I’m just going to try to look the boxes over a little bit before I open them,” Bartels said. “It’s kind of scary.”

No decision had been made by early afternoon Sunday on deliveries in Iowa, said Richard Watkins, a Postal Service spokesman in Des Moines.

“Postal Service is working with regional offices and local folks to determine what the next step should be,” Watkins said.

In Illinois, Carroll County Sheriff Rod Herrick said Sunday that most residents seemed to have gotten over their shock, although some people were asking him to use fishing line to remotely open their mailboxes as a precaution.

“It’s a typical Sunday. People are on the golf course. People are fishing,” Herrick said.

One mail carrier injured by a bomb even took his wife to dinner later Friday night “to celebrate his survival,” Herrick said.

Lee, the Thayer County sheriff, said the message conveyed by the bombs is that terrorism can happen anywhere.

“Thayer County is just a rural, farming community, and I think that’s just showing that these kind of acts are going to reach everyone – not just large metropolitan areas,” the sheriff said.

Lee’s request on Sunday that the bomber contact authorities followed a similar message from the FBI on Saturday.

“You have gotten our attention. We are not certain we understand your message. We would like to hear from you. We are listening,” said Weysan Dun, assistant special agent-in-charge of the FBI’s Omaha office. “You do not need to send any more attention getters.”

Postal officials said the bombs found Friday were accompanied by typewritten notes in clear plastic bags that 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.”

Officials described the bombs as three-quarter-inch steel pipes attached to a 9-volt battery, and said they appeared to be triggered by being touched or moved.

Two bombs found Friday in Iowa and the six found Saturday in Nebraska didn’t go off, even though at least two were picked up or moved by people reaching for their mail. Five of the Nebraska bombs were in rural roadside boxes; the sixth was in a mailbox in a residential development outside Seward.

The FBI and Postal Service urged residents and mail carriers to be cautious.

“We are asking postal patrons to keep their mailboxes open. We would recommend they tape it open,” said Rick Bowdren, inspector-in-charge of the Midwest division of the Postal Inspection Service. “That way the carrier making a delivery can look in and patrons can look in and that anxiety factor will be alleviated.”