Utility worker pierced pipe before Springfield natural gas explosion

A utility worker punctured a pipe before a massive natural gas explosion injured 18 people in Massachusetts, an official announced today. The explosion leveled a strip club in Springfield on Friday.

State Fire Marshal Stephen Coan announced today that Friday's natural gas blast was caused by "human error," after the worker pierced the pipe. However, he didn't blame the worker for the explosion, according to ABC News. 

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The worker is an employee of the Columbia Gas Company, a company which Coan seemed to suggest was the true culprit in the explosion.

The worker had damaged the underground pipe while using a metal probe to locate the source of a leak, Coan told the Associated Press. Coan said the employee was following markings on a sidewalk that were supposed to indicate the location of the gas line. However, the markings were incorrect for reasons that go unexplained by Coan. It is also not clear what caused the leak in the first place. An investigation into the leak is now being turned over to the state Department of Public Utilities, according to ABC.