Investigators: Arson caused $30 million fire at site of unfinished Los Angeles apartments

Investigators have determined that arson caused a massive fire that reduced an unfinished apartment complex in downtown Los Angeles to a block of charred wood.

Nobody was injured, but the Dec. 8 fire destroyed the wooden framing of the seven-story Da Vinci complex, causing an estimated $20 million to $30 million in damage. The intense heat also melted a freeway sign and cracked or shattered hundreds of windows in nearby office buildings.

The Fire Department announced Thursday that the blaze was deliberately set. Local and federal investigators sifted through 75,000 square feet of debris to determine arson was the cause. Details aren't being released because the investigation continues.

However, authorities say they're looking for two potential witnesses who were seen in video footage taken the morning of the fire.