– December 1998 was unseasonably mild.

That meant crews installing fiber-optic cable in St. Cloud were able to work longer into the season because the ground wasn't yet frozen.

So when a crew installing a utility pole anchor on the south side of 1st Street N. in downtown St. Cloud on Dec. 11, 1998, encountered a problem, it wasn't frozen dirt.

It was a large granite slab hidden under the sidewalk. When the anchor hit that slab 20 years ago, it bent and its tip ruptured a gas pipeline.

The crew immediately noticed dirt blowing out of the hole in the sidewalk and began to smell gas.

The crew's foreman called his supervisor and the crew blocked off the area. But the utility company and fire department were not immediately notified.

Meanwhile, the gas seeped through the crumbling foundation of Bellantti's Pizza — kitty-corner from Howie's Sports Bar & Grill — and into the basement, where it reached an ignition source, possibly a gas water heater.

About 40 minutes after the granite slab was struck, the Bellantti's Pizza building exploded.

Four people died. A woman who was trapped in the rubble was seriously injured. Ten others, including two firefighters and one police officer, received minor injuries.

Six buildings — Bellantti's Pizza & Deli, Book Em's Bar, L. Michael Hall Law office, Tom's Bar and Bartsh Bail Bonds — were destroyed, and property losses were estimated to be nearly $400,000, according to the National Transportation Safety Board.

Today, the area is a parking lot. "Seeing all that rubble and a hole — and to know about the loss of life, it was just really a shock to see that right in the heart of our downtown," said Mayor Dave Kleis, who was a state legislator at the time. "It was very surreal."

The explosion had local and national implications. It spurred creation of a city ordinance that was one of the first in the nation to address safety related to cable installation.

The explosion also led the way for a new Minnesota law that required 911 be called immediately whenever gas lines are ruptured, as well as an allocation of state money to expand the emergency response communication lines.

"I was sitting in my office when the explosion happened," said Mike Holman, St. Cloud fire chief at the time. Holman was meeting with the assistant chief and could see the firefighters who had already gathered at the scene of the gas leak from his window.

"We were talking and the explosion came in and the windows almost just did a wave," Holman said.

Other officials were less certain about what happened.

"I was at City Hall. We were in a meeting and … I thought the explosion had taken place inside the building," said Larry Meyer, who was mayor from 1997 to 2001. The confusion caused a sudden spike in use on the telephone system and many calls couldn't get through.

NSP workers Robert J. Jacobs and Karl Klang were killed instantly, as was Carolyn Sandquist, a post office employee who was on her lunch break.

A few hours later, firefighters found the body of Delbert Rose in the basement of the collapsed building, debris burying his body. Rose had lived in one of the four apartments above the restaurant.

Four people were alive but trapped inside the L. Michael Hall Law Office. Three were rescued, unhurt, within 20 minutes. A half-hour later, firefighters freed Jacqueline Ploof.

It didn't take long for state officials and national media to swoop into town. The case had nationwide implications because installing fiber-optic cables for internet, cable and telephone services was underway throughout the country. And with the increase in digging underground rights-of-way, an increase in accidents and gas leaks followed.

The NTSB's accident report, released in July 2000, pointed to a series of mistakes by the contractor and local firefighters.