Photo by Paul Clinton.

Photo by Paul Clinton.

In the hours following the Boston Marathon bombing, the NYPD increased security of hotels, transportation systems, and other vital infrastructure.

Police Commissioner Ray Kelly appeared on "CBS This Morning" Tuesday, saying he was "concerned about a similar type event."

Critical response vehicles were deployed to various locations around the city "until more about the explosion is learned," said NYPD spokesman Paul Browne in a statement reported by the Wall Street Journal.

The agency's 1,000 counter-terrorism officers have been fully mobilized, Mayor Bloomberg announced.

The New York Metropolitan Transportation Authority police increased patrols and bag inspections Monday on the Metro-North and Long Island Rail Road, the agency announced via Twitter.