NOTE: anchor outcue! Most of the streets in downtown St. Cloud are open again today as the city recovers from last week's devastating gas explosion. Investigators say they have all the physical evidence they need to figure out exactly what happened late Friday morning; they plan to wrap up their investigation this week. But it may be at least a year before they know what set off the blast in this central Minnesota town. Minnesota Public Radio's Gretchen Lehmann reports. Outcue: Minnesota Public Radio's Kathryn Herzog also contributed to this report.