Firefighters in Paris have declared the structure of Notre Dame and the cathedral's most important artworks “saved” after 400 emergency workers battled the enormous fire for nine hours. In an update Tuesday morning shortly after the final flickers of fire were extinguished, the firefighters' official Twitter account confirmed that their operation had saved as much of the iconic cathedral as possible. “The structure of the cathedral is saved and the main works of art have been safeguarded, thanks to the combined action of the different services of the State committed to our side,” they wrote. “After more than 9 hours of fierce fighting, nearly 400 firefighters from Paris have overcome the appalling fire.” However, Franck Riester, France's culture minister, warned that the building was still unstable. Photos from inside the cathedral appeared to show at least one of the building's ancient stained glass windows survived the fire largely intact. The firefighters confirmed that two policemen and a firefighter were “slightly injured.” Meanwhile, the Paris Prosecutor’s office confirmed to CNN that investigators have started to hear testimonies from construction workers working on the site.