CHICAGO (CBS) — A man who reportedly threatened to blow up a Blue Line CTA train was detained briefly on Tuesday morning.

A CTA alert reported police activity near the Monroe Street station.

Witnesses called police after a man on the train made the threats, according to preliminary dispatch reports.

The incident comes one day after the terror bombings at the Boston Marathon.

Trains were stopped briefly, causing minor delays for commuters during the morning rush.

The threat turned out to be unsubstantiated and no arrests were made

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