No bomb found after students evacuated from school, the 4th Iowa school threat this week

No explosive devices were found Thursday after a high school in eastern Iowa was evacuated because of a bomb threat, authorities said.

Police responded to Anamosa High School after the high school's staff received information about a possible bomb in the school. Bomb technicians and sniffing dogs that searched the building did not find any explosives, police said.

Students were evacuated from the building. Parents received a text alert from the school district that said, "All high school students are being relocated as a precautionary measure due to a security concern. ALL STUDENTS ARE SAFE!" according to local reports. Police called the threat an isolated incident.

Several agencies responded to the school, including the Jones County Sheriff's Office, Monticello police, Anamosa police and an ambulance from Anamosa.

More than 1,200 students are enrolled in the school district, according to the Iowa Department of Education.

The school evacuation was the fourth in Iowa this week. No injuries were reported in any of the evacuations.

On Monday, Nevada middle schools and the high school were evacuated because of a threat sent from an overseas account. Two days later, students were evacuated from the K-12 school building in the Martensdale-St. Marys school because of a bomb threat.

Also on Wednesday, students at Le Mars High School were evacuated after a 14-year-old left a threatening note in a classroom, police said. The city's police chief told KTIV that the threat said there would be a shooting in the school. That student, who was not named, has since been charged with threat of terrorism.

A Florida school shooting left 17 people dead this week.

Luke Nozicka contributed to this report.