EMBED >More News Videos RAW VIDEO: The view from NewsCopter7 shows the large crater in Fifth Avenue created by the steam pipe explosion.

EMBED >More News Videos Mayor de Blasio discusses impact of the steam pipe explosion

EMBED >More News Videos NJ Burkett reports on the people affected by the steam pipe explosion in the Flatiron District.

EMBED >More News Videos NewsCopter7 was overhead after the steam pipe explosion in Manhattan's Flatiron District.

FLATIRON DISTRICT, Manhattan (WABC) -- A large steam pipe exploded in Lower Manhattan Thursday morning, causing extensive damage to the street and positive asbestos tests that shut down streets and forced evacuations.The 20-inch steam pipe installed beneath Fifth Avenue near 21st Street in 1932 ruptured at 6:39 a.m., and Mayor Bill de Blasio said it will be several days before things return to normal in this part of the Flatiron District.The blast sent a column of scalding vapor spewing hundreds of feet into the air and left a large crater in the street. Amazingly, only five people suffered minor injuries and were treated at the scene.Authorities evacuated 49 buildings on Fifth Avenue between 20th Street and 22nd Street as a precaution. About 500 people have been displaced.The cause of the explosion is not known, de Blasio said, and Governor Andrew Cuomo directed the state Department of Public Service to conduct a full investigation and determine whether any utility activities contributed to it.Environmental tests confirmed the presence of asbestos after the rupture, which was expected given the age of the pipe."We are very concerned about the material that was part of the steam line," de Blasio said. "There was asbestos in the steam line casing."The mayor said the air is safe, but the buildings and streets are a worry."There is no meaningful presence of asbestos in the air," he said. "The concern is the debris on the street and on building facades.All the buildings, both residential and commercial, will need to be checked for asbestos before they can reopen. Impacted buildings will need to be decontaminated, which could take several days, and that means residents will not be able to get back into the homes."For people who live and work in these buildings, we are going to do our best to help them get back in as soon as possible," de Blasio said. "Most likely scenario is a couple days. Perhaps some buildings farther from the site might be opened up as soon as this evening, but that is only a possibility. More likely is it will take two days or more to really clear the buildings and be confident people can go back in."The work will require that section of Fifth Avenue to be shut down for days.The line that exploded is part of a network of more than 100 miles of pipe that provides steam to 1,600 customers.But that network is 150 years old, and leaks and explosions are becoming more common in recent years.Anyone who was in the area at the time of the rupture and the subsequent raining down of debris is advised to bag their clothing and shower."We're (decontaminating) anyone who was in the area," Office of Emergency Management Commissioner Joe Esposito said.Health officials said there is a very low risk to one-time exposure, but if asbestos got onto your clothing, you need to get rid of it."People removing the clothing, bag it up, bring it to a Con Ed site, which has been established at 22nd and Broadway," de Blasio said. "We want that clothing turned in. If there is evidence of material on the clothing, looks like the debris and dust is still visible on the clothing, we want that clothing turned in. We want anyone who thinks they are exposed, get out of that clothing, shower, clean, put on new clothing. That's out of an abundance of caution. Again, we believe that temporary brief exposure is generally not a problem. But we want to treat this with a lot of caution."Con Edison personnel were stationed at 19th Street and Broadway and at 22nd Street and Broadway until 9 p.m. to accept the clothing. They also have claim forms available for people to submit to receive compensation for their clothes.More personnel will also be in the Clinton School, 10 East 15th Street, until 10 p.m. to provide claim forms. The claim forms are also available at ConEd.com A decontamination center for first responders was set up at 22nd Street and Broadway. Video from the site showed firefighters removing their gear, and piles of clear plastic bags filled with firefighting equipment nearby.With streets being closed in the area, subway and bus service was impacted.Subway service resumed at 23rd Street, but commuters should allow additional travel time if using R and W service at 23rd Street Station. Several staircases remain closed.Several buses were also being detoured, including M1, M2, M3, M55, M23-SBS, X1, X10, X17, X27, X28.For updates, visit MTA.info.----------