Some commuters found themselves delayed as police stopped and searched trains.
Not knowing what they might encounter, police from several agencies including Norwalk and the MTA boarded a train at the East Norwalk station.
A large number of officers along with bomb sniffing dogs worked from car to car looking for any potential suspects that might have boarded in Boston.
"The train immediately after mine was searched," said Albert Douk, a commuter.
Although he didn't know why at the time, Albert Douk's morning commute along with many others was delayed, up to 45 minutes in some cases.
"There were a lot of police of course. A lot of hub bub! But, it wasn't until I was on the train that my phone started blowing up that everybody was asking me what's going on? Why are the police here?" Douk said.
Police say information received from Boston led to two trains being searched.
The second was in Darien where a police presence was increased at the station and at Noroton Heights and other busier stations along the corridor.
As an added precaution, MTA canine units were kept busy sweeping the platforms and terminals at the busier South Norwalk station for anything suspicious.
"I don't feel like I'm in danger. I don't feel like I am a lot safer. I think we are all trying to figure out how to phrase this event," Douk said.
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