One person was killed and at least 20 others injured after a steam pipe exploded underneath a street in central New York.
The explosion in midtown Manhattan sent clouds of steam, mud and rocks into the air and forced the evacuation of nearby streets and Grand Central Station.
The blast left a huge crater in the ground the size of a bus, emergency services on the scene said.
Witnesses said they were reminded of 11 September 2001, when planes hit the World Trade Center.
But the New York Mayor Michael Bloomberg said there was no reason to believe the accident was caused by anything other than a failure of the infrastructure.
Mr Bloomberg said city officials were concerned that asbestos particles may have been released into the air.