Before Wednesday’s explosion at Minnehaha Academy, gas distribution lines have experienced at least 41 major accidents in Minnesota since 2004, federal data show.

The most serious was a Dec. 28, 2004, blast that leveled an office building in Ramsey, killing three office workers. Six years earlier, a gas explosion in downtown St. Cloud killed four people, injured 15 and wrecked a half-dozen buildings.

Federal data show no fatalities or injuries requiring hospitalization in the smaller gas pipelines in Minnesota since 2011. Gas leaks may have played a role in fires whose cause was officially undetermined, such as the 2014 New Year’s Day blaze that killed three people in Minneapolis’ Cedar-Riverside neighborhood.

Operators of gas lines are required to report major incidents to the Pipeline and Hazardous Materials Safety Administration, which is part of the U.S. Department of Transportation. Distribution pipelines include those that serve individual buildings, such as the gas line tentatively implicated in Wednesday’s blast.

Mishaps on distribution lines killed 10 people across the nation last year, just under the 20-year average of 11 victims annually.