The city of Fishers ordered a stop Thursday to all underground digging by an internet provider with a history of construction mishaps after it ruptured a sixth gas line. State regulators also opened an investigation into MetroNet's practices.

The latest action comes three days after the city had demanded that MetroNet stop work after five gas line breaches in the Windermere neighborhood near Geist. The order was lifted Tuesday when MetroNet said it would use different equipment to dig into hard, dry soil to prevent ruptures.

But Thursday, city officials said MetroNet ruptured another line, causing natural gas to leak — this time in the Fox Run subdivision at Prairie Fox Drive and Mollenkopf Road. The Fishers Fire Department was sent to the scene to conduct voluntary evacuations, and Fishers filed a complaint with the Indiana Utility Regulatory Commission's Pipeline Safety Board, which will open an investigation. No work permits will be issued until the review is complete.

IURC Chairman Jim Atterholt said in a statement that "the commission takes all pipeline safety violations very seriously and has already begun its investigation into the incidents." The commission's Pipeline Safety Division visited the Fishers site Thursday.

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"This is a very serious issue, a life safety issue, when you have this many ruptures by one company in a short period of time," said fire Chief Steve Orusa.

After the first rash of ruptures, state Sen. Jim Merritt, R-Indianapolis, described the leaking gas fumes as a “very dangerous situation,” and said he would report them to the IURC. He said workers were digging in very dry soil to bury fiber optic lines when they struck the gas pipes. “You’ve got metal striking metal, which causes sparks, which causes explosions,” Merritt said, adding the workers were chipping at the dirt rather than scooping it.

After meeting with the city and Merritt, MetroNet agreed to use "hydroexcavation,” a digging method with water pressure and a vacuum, a step the company called "extraordinary."

"Despite the higher cost associated with these procedures, we believe it is the safest way to move forward with construction in Fishers until the ground softens," MetroNet spokeswoman Mindy Wingert said in an email.

MetroNet said in a statement Thursday afternoon it had fired the contractor for disregarding the directive to use the hydro-powered equipment.

Orusa said firefighters told residents to leave their houses if they detected the rotten-egg smell of natural gas inside. "That means it's inside, and there are so many ignition points in a house," such as a stove burner, that could cause a deadly explosion, Orusa said.

Lee Jorgenson, 32, said he and his family were evacuated from their home in Fox Run at 9:30 a.m. Thursday.

"The smell was very strong, and it was in our house," said Jorgenson, who lives directly in front of the ruptured line. "A firefighter knocked on the door and said, 'I think it's time to leave.'"

Jorgenson said access to the subdivision was blocked while firefighters with gas detectors took readings of the air quality.

He said before he could start his car, the fire department took a reading to make sure it was clear.

"But a lot of other people they wouldn't let drive," he said.

Jorgenson did chores, ate lunch and was allowed back in at 12:30 p.m.

"I don't know if I was scared, but it was very alarming," he said.

Evansville-based MetroNet is laying underground fiber optic cable lines to provide phone, cable and internet service to most of Fishers’ 90,000 residents. The company has faced similar complaints in Central Indiana during the past three years.

Two years ago, MetroNet was ordered to stop work when it ruptured gas lines and struck other utilities four times in Westfield, said Mayor Andy Cook.

“We put our foot down and said you have to stop working until this is fixed,” Cook said. “They got the message and it resolved itself.” He said workers wrongly estimated the depth of the utilities.

Greenwood ordered the company to stop work in the southern suburb after it ruptured water and other utility lines in 2015. Residents also complained that MetroNet wasn't replacing dirt after digging and that workers were rude.

“There were quite a few issues like that, but they were resolved, and they are still doing work here,” said Greenwood Corporation Counsel Krista Taggart.

Cook said construction crews striking underground utilizes isn’t uncommon. “It happens about three or four times a year. It’s amazing there aren’t more explosions,” he said.

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Merritt said he wants a review of the company’s safety measures. "I was incensed to hear about this — that they hadn't gotten it right after what happened previously," he said.

Merritt said one of the worst accidental gas explosions in Indianapolis history is never far from his mind.

In 1997, Gladys Mills, 84, was killed and six houses in the Charter Pointe subdivision on the northeast side were destroyed when workers ruptured a gas main two weeks earlier, leaking gas underground.

MetroNet started in Greencastle in 2005 and is now in more than 30 Indiana municipalities and a handful of Illinois locations. The provider's one-gigabyte internet speeds are faster than what Comcast and Spectrum, formerly Brighthouse, typically offer. In 2015, it announced plans to expand the network into in Westfield, Carmel, Fishers and Zionsville. It is also exploring expansion into Noblesville.

Call IndyStar reporter John Tuohy at (317) 444-6418. Follow him on Twitter and Facebook.