Despite the widespread disruptions, the police reported no serious injuries.
This can lead to widespread disruption across the network and potentially a huge loss in revenue.
But widespread disruptions were expected later in the morning.
At least at first, the innovations will likely cause widespread disruption, perhaps even political instability.
"The next attack will result in even greater casualties and widespread disruption to American lives and the economy," they wrote.
Last month heavy snow caused widespread disruption across much of Britain, helping to produce this effort.
The strike, by about 700,000 workers, began on Wednesday and has caused widespread disruption.
There's no evidence of widespread disruption during that period.
The result, they say, was widespread disruption by workers, scattered strikes and in some cases the destruction of factories.
Heavy snow fell overnight across large parts of the country, causing widespread disruption to transport and education.