One person has been killed and at least 20 others injured when a steam pipe exploded underneath a street in central New York during the evening rush hour.
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 Terminal.
The New York Police Department said the incident was not terrorism-related.
Millions of pounds of steam are pumped beneath the streets of New York to help heat and cool thousands of buildings.
The 83-year-old pipe exploded just before 1800 (2200 GMT), sending people running from the scene as steam billowed up from the ground.
The blast left a crater in the middle of Lexington Avenue and sent clouds of steam, mud and rocks into the air.
Two of the injured are reportedly in critical condition.
It is still unclear exactly what caused the accident, but it may have been due to cold water entering the pipe or a break somewhere else in the system.
It is the largest commercial steam system operated by utility company Consolidated Edison.
'Like a volcano'
Firefighters and emergency crews closed off part of the street between Grand Central and the Chrysler building.
Thousands of commuters were evacuated from the rail hub after workers yelled for them to get out.
A witness, investment banker Heiko Thieme, said the explosion was like a volcano erupting.
"Everybody was a bit confused, everybody obviously thought of 9/11," he told the Associated Press.
Reggie Evans also likened the effect to the attacks on the World Trade Center.
"I saw rocks and pebbles coming down. As I was running I got pelted in the head by rocks and concrete," he told the Reuters news agency.
"Steam came up and then the ground started breaking up."
New York Mayor Michael Bloomberg later ruled out the possibility of a terrorist attack.
"There is no reason to believe whatsoever that this is anything other than a failure of our infrastructure," he told a news conference.
"The big fear that we have is whether there may or may not have been asbestos released."
Environmental officials have told local residents and workers to stay out of the area or remain indoors while they undertake tests for the construction fibre that has been used to insulate such pipes in the past.
In 1989, three people were killed when a steam pipe ruptured in the city.
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I was in a building on the corner of Madison and 41st. I was on the phone when the rumbling began, like a space shuttle about to lift off, or worse yet, like a building collapsing. From the 8th floor I looked out and saw hundreds of people running. We opened a window and a hundred yards away all you could see was darkness, clouds of smoke between the buildings. We all ran for the exits and were in a panic to leave the building. The rumbling never stopped, it felt like it was going to overtake us any second. When we got to the streets, we soon realized the smoke was controlled and watched as the firefighters fought to put it out.
Jason Greer, Brooklyn, NY, USA
I work at 41st and Lexington Ave. I heard a sound that sounded at first like thunder, then like a jet engine. Looking out the window I saw a huge billowing cloud of white smoke coming right at my window on the 36th floor. Everyone ran to the stairwell and got down safely. There was some panic on the street but it soon became clear that it wasn't terrorism.
Josh, NYC, USA
I live very close to where the steam explosion took place. Everything seems to be running back to almost normal now. The fire department, the police and the rest of the authorities are handling the situation quite well. Shops remain open and the usual traffic is resuming along the streets. City personnel remain to usher the cars and people on where to go for safety.
Mazie, New York, USA
The streets are packed with emergency vehicles and many roads are closed off. There is an enormous plume rising from the affected area. Everybody is calm though and the police here are well used to dealing with this kind of emergency. The trains are running although entry into Grand Central is restricted.
Simon Darnell, NY USA
I was about five blocks away in a coffee house at the time of the explosion and had no idea what had happened until I spoke to some people that entered the coffee house in a very distressed state. I went outside and there were thousands of people walking uptown. There was lots of what appeared to be smoke. I later heard it was steam bellowing upwards over the tall buildings. It did feel like something suspicious had happened. I got on the 51st V train and got to Queens in less than ten minutes.
Kevin Lynch, NY, USA
I work in Chelsea (W23rd St) and had a friend call me and tell me about the explosion. I immediately thought of the worst case scenario and the memories of 9/11 immediately came to my mind. Luckily, it doesn't seem to be terrorist related and the only major disruption I encountered were on the trains.
Joe, NY, USA
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