Bartlesville Public Schools were closed Wednesday over what the district called "credible reports of a threat."
School leaders said the decision was made after someone saw a man with a gun not far from the high school Tuesday afternoon.
Police have not found that man or any evidence of an actual threat, but, as a precaution, 6,000 students stayed home Wednesday.
No one heard shots and there's no indication children were ever in danger, but despite that, classes were called off, starting Christmas break a day early.
Police officers were all around Bartlesville High School Wednesday, even though the building was closed.
They continued to check a report that two men, one of them with rifle or shotgun, were spotted Tuesday behind the school, beyond the practice fields in a wooded area near the Pathfinder Trail.
The men got into an SUV, which was picked up on a school surveillance camera.
The police have not determined who was in the truck or what they were doing.
"There has been no new threats made to the school. This is what we would typically consider a suspicious incident, but until we locate these two subjects and find out exactly what they were doing, we take it seriously," said Bartlesville Police Captain Jay Hastings.
School officials and police said, without knowing if there was an actual threat, they chose the most cautious route.
"And our local police promised a lot of police presence today, even more than we've had the last few days, but even with that, we were fearful that something could happen to our students and we weren't willing to take that risk today," said Superintendent Gary Quinn.
The fear is amplified after the arrest last week of 18-year-old Sammie Chavez, who police say was planning to attack students at Bartlesville High, and after last Friday's tragic shooting at Sandy Hook Elementary School in Newtown, Connecticut.
Warren Collier is the father of a 6th grader, and he was happy with the decision to cancel classes.
"It may be nothing, because of where the property is located. The river is back there and maybe they were just hunting, but it does concern me," Collier said.
The police patrols and investigation will continue, but in the meantime even a basketball game planned for Friday has been postponed.
And the superintendent said he hoped things would get back to normal for the restart of classes January 2nd. But police said there will be more officers at the school regardless.