Crews helped hundreds of people, including staff and county residents, evacuate the building. Then, responders went through the courthouse, room by room.
A handful of residents gathered across the street to watch crews handle the scene.
"It's horrifying and whoever did that, they need to be put up under the jailhouse," said onlooker Patricia Matthews.
Kerns said the Muskogee Hazmat team did an air quality test of the building, which turned up nothing.Kerns said drug court had been going on Friday, so it is possible whomever made the threat was trying to miss a court date. He said the emergency response is a good learning experience for area crews, because with the ongoing sense of frustration with government nationwide."Things in Washington and places like that. We want to be ready in the event something ever would happen," Kerns said.
Authorities issued an all clear around 1 p.m. but the courthouse remained closed for the rest of the day.