Students and staff evacuated from a high school in Rochester, Minn., after a bomb threat Wednesday morning are returning to school, school district officials said.

Police gave the “all clear” about 11:30 a.m., two hours after using K-9 dogs to sweep John Marshall High School. Police did not find anything that would indicate the bomb threat was credible, the school district said in a statement.

The school was emptied around 9:30 a.m. when somebody called in the threat.

“We take all threats very seriously, as a result, we are evacuating the building and working the Rochester Police Department to sweep the building,” an earlier statement said.

Students and staff were taken to multiple locations across the district while the building was searched. All were reported safe, the district said.

Staff and students were returning to the school and “we are working on alternate lunch schedules for all of our students,” the district said.