SAN DIEGO, May 20 (UPI) -- A natural gas leak caused an explosion in a hotel under construction in downtown San Diego, not an act of terrorism as some feared, investigators said.
Fourteen people were injured in the blast that damaged several floors on one side of the 30-story structure, the San Diego Union-Tribune reported Tuesday.
Officials said the explosion occurred in a room where the building's utility equipment is located. Investigators indicated they suspected leaking gas ignited by a boiler or from an electrical source.
"That gas found an ignition source," San Diego Fire-Rescue Department spokesman Maurice Luque said. "We're not sure what it was, but it could have been electrical or the flames from the boilers."
About 400 workers were inside when the explosion occurred Monday, officials said.
Damage was estimated at $5 million.
The California Occupational Safety and Health Administration said it would interview injured workers and inspect the site once it is determined to be safe.
Moments after the blast, downtown residents said they thought they were under attack.
"In these post-9/11 days, you wonder, 'Who did what and what did they do?' " said Dan D'Amato, who watched ash and particles land on his condominium patio.