Timeline of events leading up to gas explosion

SPRINGFIELD, Mass. (WWLP) - 22News is working for you with a look at the timeline of events that led up to the blast.

"We have determined that human error is what the cause of the explosion was."

An investigation by the State Fire Marshall's office determined a Columbia gas worker accidentally created a tiny hole that led to a devastating explosion.

The worker was called Friday afternoon to Worthington Street after reports of the smell of gas in the area.

"He began searching the outside of the building using a metal probe to make holes in order to measure gas."

That worker was unaware at the time he was drilling right into a gas line.

"His measuring seems to be at an appropriate distance from where old markings were on the sidewalk indicating where the gas line from the main went into the building."  However the markings were incorrect,” Mass. Fire Marshal Stephen Coan said.

Once crews were able to reach this pipe, as you can see it's pretty clear how this happened, the metal probe puncture this pipe and it went straight through.

That's when people in the area were evacuated.

Fire commissioner Joseph Conant told 22News, it took Columbia gas between 20 and 30 minutes to shut the gas off in that time, enough had already built up in the Scores strip club that any small spark could have set off this explosion.

"It looks like a warzone right now," said a Springfield resident.

"Absolutely unbelievable and it's amazing that no one was killed,” Robert Radowski of Springfield said.

21 people were injured, Scores was leveled and at least 3 buildings were condemned.

The state's department of public utilities is now leading the investigation into the response by
Columbia Gas including why the markers indicating the location of the gas pipes were incorrect.

"This will be a thorough investigation and it will be concluded quickly."

And here's a quick timeline of how this played out.

• 4:09: gas company arrived on scene
• 4:20: worker punctures pipe
• 20 to 30 minutes to shut off gas
• 5:25: time of explosion