Authorities have arrested the man they say threatened to blow up the Department of Natural Resources headquarters in Saint Paul. State officials closed five state buildings as a precaution to what they described as a serious threat from the disgruntled, former employee. They also say the man was an explosives expert. Minnesota Public Radio's Tim Pugmire reports... Police arrested the 33-year-old former D-N-R employee this morning at a residence in Stillwater, after getting an anonymous tip. The suspect allegedly made terroristic threats against state employees and facilities yesterday, prompting officials to close five buildings, including the D-N-R headq