Rock Hill School officials say a lack of communication is what led to a school bus dropping off students at South Pointe High School Wednesday amidst a campus-wide lock down.

Police say a Tweet threatening violence after school is what led to the abrupt lock down — but district leaders say a bus driver transporting students from the Applied Technology Center never got that message.

District spokeswoman Elaine Baker said students were allowed to disembark — but in the hours since — those policies have changed

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Baker said the bus driver did notice the increased presence but told WRHI’s Andrew Kiel the driver still allowed the students to head inside the campus.

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15 police officers responded to the South Pointe campus that was locked down for nearly a half hour.

Baker says in future campus lock downs, an additional step has been added to notify the transportation department — and if bus drivers see any police activity, students will not be allowed to disembark.