CHICAGO (CBS) — A man on a Metra train Monday night was only trying to ease his fears about a bad dream he had, but the note he passed to the train conductor was mistaken for a bomb threat.

Police in Riverside said the man, who is deaf, had apparently fallen asleep on the Burlington Northern-Santa Fe line train and dreamt it was exploding. When he woke up, he was worried that the dream might come true, and wrote a note to the conductor about it.

But the conductor took the note to mean there was a bomb on the train and took it as a threat.

Thus, the conductor flagged down a Riverside police officer at 8:12 p.m. Monday, and reported that the passenger had handed him a note saying there might be a bomb on the train, Riverside police said.

The train was stopped at the crossing at Burlington Street and Longcommon Roads, and officers began a response for potential explosives.

The train later left the area, but Burlington Northern Santa Fe Police detained the man for further questioning.

The train was swept by bomb-sniffing dogs once it arrived at its final destination in Aurora. The sweep came up negative.

Railroad police later told Riverside police that no charges were brought against the passenger, a 20-year-old Brookfield resident.

“Police will always respond to these types of incidents with great concern and with the anniversary of 9/11 just passing; any mention of explosives will generate heightened attention,” Riverside Police Chief Thomas Weitzel said.

The Sun-Times Media Wire contributed to this report.