Ipswich Grammar School posted on its Facebook page that all staff and boys had been evacuated following a telephone threat.

“Queensland Police are on site and assisting us with managing the situation,” the post said.

A Queensland Police Service spokesman said police responded to the threat about 8.15am and were on site as a precautionary measure.

Sue Hamling commented on the Facebook post and said "drop past this morning. Police everywhere" while Paula Fisher posted "the boys will be safe with the amazing staff there ... fingers crossed it will be over soon...".

About 9.45am Chrissie Morgan posted that those who were evacuated were still on the oval.

School staff responded on Facebook to a request from a concerned parent about what was happening about 10am.

"We appreciate this is a stressful time for parents," the post said.

"There are no updates as yet. QPS is working with our staff to ensure the situation is handled safely and quickly."

The school was "thoroughly" searched by police and students returned to studies by noon.

Students returned to school after three weeks' holiday for the start of term three on Monday.