Some parents are choosing to keep their kids home today after a threat triggered concern at Lucerne Elementary School and within the Upper Lake Unified School District. District leaders say the threat, linked to a social media post, has been investigated and isn’t considered credible. Still, there will be a noticeable law enforcement presence on campus as a precaution. Investigators are continuing to follow up with help from probation and sheriff’s deputies. School officials say they’re taking it seriously and want families to speak up if they have information.