America hit by mailbox bombs

Blasts are being treated as domestic terrorist incidents

At least six pipe bombs have exploded in letter boxes in the United States, in rural areas of Iowa and Illinois.

More 'attention getters' are on the way

Note attached to bombs

The devices were left with messages criticising the federal government.

FBI spokesman James Bogner said the blasts were being treated as domestic terrorist incidents.

Several people were hurt, but they are not thought to have been seriously injured. Some of the wounded are postal workers.

Bomb note

Officials say the pipe bombs were not mailed, but were placed in the letter boxes and primed to go off when the letter boxes were opened.

The Unabomber waged his campaign for 17 years

The bombs were reported to have been accompanied by a typewritten note that read: "Mailboxes are exploding! Why, you ask?

"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 'attention getters' are on the way.

"If I could, I would change only one person, unfortunately the resources are not accessible. It seems killing a single famous person would get the same media attention as killing numerous un-famous humans."

The FBI says at least eight devices were planted - not all detonated - but that there may be more.

Some postal deliveries in the area have been suspended.

Attacks from within

In recent years the United States has been prone to bomb attacks carried out by its own citizens.

In 1998, Theodore Kaczynski, known as the Unabomber, was sentenced to four terms of life in prison without parole for a 17-year bombing spree which left three people dead and many injured.

Last June, Gulf War veteran Timothy McVeigh was executed for the 1995 bombing of a federal building in Oklahoma that killed 168 people and injured hundreds of others.

Following the 11 September attacks on the United States, the country was hit by a series of anthrax attacks.

The FBI has said it believes those attacks were probably the work of a US national.