Chicago ? Authorities on Friday were investigating whether there was a link between two similar explosive devices mailed this week with notes to office buildings in Chicago and Kansas City, Mo.

The devices were sent through the mail – the first on Wednesday to the American Century Investment’s mail facility in Kansas City and the second on Thursday to a downtown Chicago high rise, said U.S. Postal Inspection Service Inspector Wanda Shipp.

Both devices were diffused without incident, she said.

Shipp would not discuss the note that came with what she called an “explosive device” sent to the 65-story high-rise at 311 South Wacker Drive in Chicago’s business district. Nor would she say which business the device was mailed to or whether it was mailed to an individual in the building.

Shipp also declined to say if the note sent to the Chicago building contained any threatening language. But in Kansas City, FBI spokesman Jeff Lanza characterized the note sent with the device there as threatening.

Officials suggested in both cases that the devices were not working bombs that could have exploded.

At a news conference on Friday, Chicago Police Superintendent Phil Cline said the device that arrived in the mail at 311 South Wacker Drive “did not contain any explosives.”

“But we’re working with ATF (U.S. Bureau of Alcohol, Tobacco, Firearms and Explosives) and with the postal inspectors to see if it matches any other devices that might have been around this country,” he said, declining to comment further.

A day earlier, Postal Inspector Don Obritsch in Kansas City characterized the device delivered to American Century as an “actual I.E.D, improvised explosive device,” but it appeared it was designed more to frighten rather than kill.

“That was the real deal, but it was not primed to go off,” Obritsch told The Kansas City Star. “To some extent, it was a device meant to scare people.”

Jeff Lanza, an FBI spokesman in Kansas City, agreed that the bomb there appeared designed to threaten. Still, he said, “It was a functional bomb.”

In Kansas City, the FBI would not say whether the bomb was addressed to an individual at American Century or the company as a whole. In Chicago, Shipp would not identify the company the device was sent to or whether it was addressed to an individual at that company.