4:15 PM update: Police in Steuben County have identified the suspicious yellow granular substance that was found in a mailbox in the area of 700 East and 500 South. 

It's urea nitrate, which is an ingredient that is sometimes used in explosives. 

The Steuben County Sheriff's Office says the urea that was found in Steuben County was not explosive in its current form. But, it should not be handled or destroyed by anyone except law enforcement. 

If you have found a suspicious yellow granular substance, contact your local law enforcement for further instruction.

Our earlier story…

HAMILTON, Ind. (WOWO): Police are investigating a suspicious substance that was found in a number of mailboxes in the area of 700 E and 500 S in Steuben County.

A hazmat crew found what they're calling a yellow, granular substance in several mailboxes throughout the area.

All of the mailboxes were washed down and a sample of the substance was taken to the lab. Police haven't said what the substance was or who placed the material in the mailboxes.

Anyone who finds a similar substance in their mailbox is asked to call police or the fire department.