Chief NYPD spokesman Paul Browne said critical response teams are deployed around the city until more about the explosion is learned. Officials are stepping up security at hotels and other prominent locations.
British police also say they are reviewing security plans for Sunday's London Marathon. It's the next major international marathon. A London Metropolitan Police spokesman says police are working with marathon officials to review security plans.
The blasts occurred at the finish line of the Boston Marathon on Monday afternoon. It was not yet clear what caused the blasts.