Commissioner James O’Neill says the New York Police Department is closely monitoring developments in the London subway explosion.

O’Neill said on Twitter on Friday that there’ve been no direct threats to New York City.

But he says people should always be vigilant and aware of their surroundings.

Officials say a homemade bomb exploded on a packed London subway train during Friday morning’s rush hour, leaving more than 20 people injured. Police said the explosion was a terrorist attack, the fifth in Britain this year.

(AP)