Two people are confirmed dead after an explosion at the Givaudan Colour Sense plant in Louisville.(Jon Cherry / LPM)Louisville officials say it will take time to determine what caused the deadly explosion at the Givaudan Colour Sense factory in the Clifton neighborhood.At a press conference Wednesday morning, Mayor Craig Greenberg confirmed that the explosion killed two workers at the plant on Payne Street Tuesday afternoon.He said one person died after being transported to University of Louisville’s downtown hospital. Fire teams found a second person under the rubble late Tuesday night.“We had all been told by the business that all of the employees were accounted for. Tragically, that was not the case,” Greenberg said at the press conference.Ten other people were transported to the hospital with injuries from the blast, falling debris and burns.Residents heard the explosion from blocks away. Homes shook and windows shattered.Greenberg said residents whose homes sustained damage should leave the debris alone and call to report it to Metro Safe at 502-574-2117.“Getting a handle on all of the debris is going to be incredibly helpful to all of the investigators as they piece together what happened,” Greenberg said.Officials don’t know what caused the explosion. The Louisville Fire Department is leading the investigation with assistance from the Bureau of Alcohol Tobacco and Firearms.ATF Special Agent Shawn Morrow said the agency’s response team will be deployed in Louisville during the investigation.“They have some unique capabilities for these types of incidents. The teams are made up of ATF special agents, fire investigators, explosive specialists and bomb technicians,” Morrow said.Fire Chief Brian O’Neill said the cause of a similar explosion at the same factory in 2003 was due to a chemical that, according to O’Neill, is no longer used at the plant. Additionally, he said there are no hazardous materials present at a level that would negatively affect the air or environment around the plant.Greenberg said the city invited representatives from Givaudan to the press conference Wednesday, but they did not attend.