Crews Work Business Fire

***UPDATE FRIDAY 5:47 P.M.***Assistant Fire Marshal Brian Davison said the fire was electrical in nature. Investigators are not sure which circuit in the ceiling failed because so many circuits were running through the area. Prosecutors also had relocate offices. Employees who collect child support moved into the Boone County courthouse. They did not go to work on Friday because they were still setting up computer stations. Officials confirmed the fire did not destroy important physical evidence, including guns and DNA samples.Another law fire around the corner also closed Friday after employees got headaches from the smoke.***UPDATE FRIDAY 12:07 A.M.***Crews have reopened Walnut Street in downtown Columbia.***UPDATE 11:16 P.M.***Firefighters have released further details after investigators combed through the structure on Walnut Street. They say an assistant prosecutor was at the courthouse and noticed the large amount of smoke coming from vicinity of the Columbia Police Station and called 911.Fire crews arrived on the scene at 8 p.m. and reported heavy smoke from the structure. Crews entered the structure and found the fire in the attic area of the building. Crews cut a hole in the roof in order to ventilate the attic space and aid in the location of all of the remaining fire. Crews working from the inside the structure and on the roof were able to successfully contain and extinguish this fire, in the building of origin. Assistant Fire Marshal Brian Davison is investigating the fire, and has determined that the fire did start in the attic area but the exact cause remains under investigation. He has also issued a preliminary damage estimate of $100,000.00. ***UPDATE 10:21 P.M.***Columbia Fire Battalion Chief James Weaver confirmed with ABC 17 News crews at the scene of the fire, that they were dispatched at 7:57 p.m. and were on the scene at 609 Walnut Street within three minutes. Firefighters battled the blaze which was mostly concentrated inside the attic of the Trapp Law Firm, by cutting a hole in the roof, and opening doors to other businesses on the block to help ventilate the structure. 19 firefighters worked the incident, and command staff called an extra fire truck to the scene to help. Crews had the fire under control within about an hour. No one was inside the building at the time of the fire, and no one was injured, although some legal files may have been damaged. Columbia Public Works plans to treat the roads around the building to melt ice that formed from water firefighters put on the blaze. ***ORIGINAL STORY***Fire crews responded to reports of a fire across from the Columbia Police Department at about 8 p.m. Thursday. Scanner traffic in the ABC 17 newsroom indicated that police saw smoke coming from law offices at 6th and Walnut streets. Firefighters responded immediately and called for police to close off the entire city block between 6th and 7th streets, and Walnut and Ash streets. Firefighters are connecting hose lines, and ABC 17 News crews are on the scene working to get more information. Check back with abc17news.com and tune in to ABC 17 News at 9 and 10.