A Gwinnett County elementary school was locked down Wednesday after a parent allegedly threatened to harm a student, officials said.

School and local police responded to Baggett Elementary in Norcross and students were kept off the playgrounds and inside the building during the school day, Principal Charlotte Sadler said in a letter to parents.

The parent accused of making the threat never appeared on campus, Sadler said.

The incident was one of three Wednesday involving threats against students and schools.

In Pike County, about 55 miles south of Atlanta, a ninth grade student allegedly posted a threat on Instagram that another student saw and reported, 9th Grade Academy Principal Sheryl Watts told The Atlanta Journal-Constitution.

School officials in the superintendent’s office issued an “all call” about 7:20 a.m., notifying parents that the situation was under control, Watts said.

“A student made a post on Instagram and another student saw the post and alerted their parents,” Watts said. “From there, the parent contacted local law enforcement.”

After officials with the sheriff’s office visited the freshman who allegedly made the threatening post, deputies told school officials there was nothing to worry about.

Officials in Athens also investigated alleged threats against Cedar Shoals High School.

“We are speaking to a student who was alleged to have made comments about ‘coming and shooting up the school,’” Athens-Clarke County police spokesman Epifanio Rodriguez told The AJC on Wednesday afternoon.

Police and school officials are continuing to investigate the allegations, Rodriguez said.

In October, two students at a high school in Cherokee County were arrested after plans to detonate an incendiary device were discovered along with a hit list of students and staff.

Alfred Dupree of Acworth and Victoria McCurley of Woodstock each face three counts of criminal attempt to commit murder and four counts of making terroristic threats and acts. They also face charges of criminal attempt to commit arson and possession or transportation of a destructive device or explosive intending to kill, injure or destroy any public building.

Two students died Tuesday in the year’s first fatal school shooting in the United States.

Seventeen students were also injured, 12 of them hit with bullets and five others hurt in the scramble as hundreds of students fled from Marshall County High School in Kentucky.

Police quickly captured the suspect, charging him with murder and attempted murder, but did not release information about his identity or possible motive.

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