According to a tweet from Christopher Dormer, the school district's superintendent, everyone is safe.
"Everyone is safe at NAHS. No threats have been found. Staff and students have been amazing in their cooperation and understanding," a tweet said.
By noon, students were being dismissed.
"Student dismissal underway at NAHS. Buses being loaded first, then parent pick up will be permitted. Shelter in place at Whitehall and Admin Building now lifted," another tweet said.
It was not immediately clear what the threatening call referenced, or who made the call.
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