Asbestos found at steam pipe explosion in Manhattan's Flatiron District
A steam pipe explosion near Fifth Avenue and 21st Street in Manhattan, New York, left a crater in the middle of the street and sent smoke spewing from the ground, according to a report from NBC New York.

Asbestos was found on the ground near the site, according to the report. Consolidated Edison, the power company that maintains the steam line, will check for other contaminants, Reuters reported. Twenty-eight of the buildings in the "hot zone" are being decontaminated and the area will likely remain evacuated through the weekend, NBC News reported.

Although the air has no signs of asbestos, New York Mayor Bill de Blasio said carcinogen-tainted debris could have been thrown stories high, contaminating air conditioners and buildings. De Blasio told reporters at the scene that of the 49 evacuated buildings, 21 on the outskirts of the area might open by Thursday evening.

"Now that we know there's asbestos present, we're not going to cut any corners," de Blasio told reporters at the scene. "We're going to be thorough."

Five people sustained minor injuries, including one police officer who did not require hospitalization, according to the NBC New York report.

The explosion, which occurred around 6:30 a.m. ET, shut down the Flatiron District of the city, leaving debris, chunks of asphalt, and mud covering nearby streets and cars. Water also filled the street, but there has been no confirmation of a main break at this time. The swiftly changing color of the smoke indicated a possible fire underground, NBC New York reported.

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The New York Fire Department responded to the explosion, according to NBC News. The cause of the blast is under investigation.

Fire Commissioner Daniel Nigro told Reuters that 100 firefighters and some civilians have been decontaminated. Officials said anyone in the vicinity should bag their clothes and send them to Con Edison, NBC New York reported. Two decontamination sites have been set up, according to officials, on 19th and 22nd streets.

Read the full NBC New York report here.

-- Reuters contributed to this report.