The four-alarm fire that stopped transbay service on BART for nearly 12 hours earlier this month has officially been ruled as arson, according to the team of ATF agents and local authorities tasked with investigating the fire. According to Bay City News, investigators aren't yet releasing the details of the evidence that led them to the arson conclusion, as the case is still ongoing.

No new information was available on the potential suspects responsible for nearly $25 million in damages to the nearly completed Red Star Senior Living complex, so we assume authorities are still on the look out for a trio of (possibly teenaged) firebugs.

As the ATF agent in charge of the San Francisco Field Division explained to Bay City News: "Although the fire scene is wrapping up, there is still a lot of investigative work to be done on this senseless act of violence... We are committed to working this investigation with our fire and law enforcement partners to ensure the public's safety while trying to determine who is responsible for setting the fire."

Previously: All BART Fire coverage on SFist
[Bay City News/NBC]