(Photo by Russ Mitchell) Spencer firefighter Ben O'Clair, Jeff Cullen of the state fire marshal's office, Mark Stover of the Spencer Fire Department and Lt. Mike Wilson of the Spencer Police Department watch a monitor as a robot camera looks into mailboxes a few blocks away. Five teenagers left explosive packages in handful of mailboxes around the county. The stunt caused property damage and tied up emergency resources, but no one was injured.

Daily Reporter Staff

The Iowa Department of Public Safety issued a safety alert through the State Fire Marshal's Office in response to explosive devices found earlier this month in mailboxes across Iowa.

The alert follows a March 8 investigation, which identified a group of teenagers who put packages with an unstable mix of drain cleaner and aluminum foil into area mailboxes in Clay County.

Postal deliveries were stopped and emergency response officials spent a day searching 1,200 area mailboxes.

Investigators with the Clay County Sheriff's Office, Spencer Police as well as Iowa State Patrol troopers, agents with the State Fire Marshal's Office and U.S. Postal Inspectors determined 17 mail boxes were targeted.

They charged five juveniles from the Ruthven and Ayrshire areas with 17 federal felony violations and seven state felony violations. All five await trial.

The state fire marshal's office said a more recent incident occurred early Monday when State Fire Marshal investigators were called to assist the Benton County Sheriff's Office, which is just west of Cedar Rapids.

Four mail boxes were destroyed by unknown devices along a three-mile stretch of road in the eastern part of Benton County, according to the state fire marshal's office. No injuries were reported and no suspects have been identified.

A similar incident occurred on the south side of Des Moines on March 14 but investigators have found no link between any of the cases.

"In most cases, these incidents are the result of juveniles placing homemade devices in mail boxes to see what happens." said Eugene Meyer, Commissioner of Public Safety in a statement released earlier this week. "What these kids fail to realize is law enforcement takes their response to these incidents very seriously and will file criminal charges on those found to be responsible. As demonstrated by the case in Spencer, serious felony charges will likely result. Not to mention the risk of someone being seriously injured or killed by one of these devices."

If you find a suspicious device in your mailbox:

* Do not touch or remove the device.

* Leave the mail box door open, leaving the mail box as you found it.

* Call 911 immediately.

* Keep others away from the mail box.

* Call a local law enforcement agency if you see any suspicious activity near your residence.