New Jersey Transit police have been busy checking reports of unattended bags one day after the Boston Marathon explosions.

 

A crowded NJ Transit platform (Twitter)

NJ Transit spokesman John Durso Jr. says all were cleared without incident.

Durso also says the mass transit agency has seen a slight increase in calls to its 888-TIPS-NJT tip line in the last 24 hours. Durso says most were from people testing the number or adding it to their contact lists.

State Police Lt. Stephen Jones says there is no known threat. But the agency's bomb unit, aviation crews, tactical teams, and search and rescue assets have been deployed as a precaution.

The Port Authority also is on a heightened state of alert at airports, bridges, tunnels and on its PATH rail line between New Jersey and New York.

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