Investigators have been unable to determine the cause of a fire that charred some 20 acres on UC Santa Barbara’s West Campus on Thursday night, according to the Santa Barbara County Fire Department.

The cause of the blaze has been listed as “unknown origin/undetermined,” fire Engineer Russ Sechler said Saturday.

He added that a witness told investigators that “it appeared there were fireworks going off in the area prior to the fire,” Sechler said.

No structures were damaged in the blaze, although one home was evacuated as a precaution.

The fire was declared fully contained Friday evening.

The flames burned largely in and around the Coal Oil Point Reserve, and UCSB officials were assessing the damage to the environmentally sensitive area as well as research projects that were being conducted nearby.

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