MDU Construction Services Group acquires Desert Fire Holdings

April 12, 2006—MDU Resources Group, Inc. has acquired Desert Fire Holdings, Inc., headquartered in Reno, Nevada. Desert Fire specializes in the installation and maintenance of automatic fire sprinkler systems in Las Vegas and Reno.

Desert Fire will become a part of MDU Construction Services Group, Inc., a wholly owned subsidiary of MDU Resources. “This acquisition is a great fit with the work done by two of our other Las Vegas companies, Bombard Electric and Bombard Mechanical,” said John Harp, president and chief executive officer of MDU Construction Services Group.

“We’re excited about Desert Fire joining our team. It will help strengthen our role in these Nevada high-growth markets. With the Desert Fire acquisition, we’re approaching 1,500 highly skilled workers in the fastest growing market in the United States.”

Desert Fire was founded in 1980 with a staff of seven and has grown to more than 200 today, with annual revenues in excess of $35 million.

MDU Resources Group, Inc., a member of the S&P MidCap 400 index, provides value-added natural resource products and related services that are essential to energy and transportation infrastructure. For more information, visit the company’s Web site.