“Police attended and found a group of youths near the school, and a realistic-looking air rifle which had been dumped by the group.
“Police are speaking to the youths.
“The school lockdown has since been lifted.”
The air rifle at the centre of this morning’s scare was capable of firing small metal slugs, said a police spokesperson.
Meanwhile all the schools nearby were forced to take evasive action.
“MRI has gone into lockdown. We will provide updates in our Newsfeed,” a message posted on the school’s website read.
Mt Roskill Grammar School principal Greg Watson said police had asked the school to go into lockdown due to an unspecified nearby risk.
“We were in lockdown for 20 minutes from 9.35 am at the request of the Police, due to an event in the community,” Watson said.
“The lockdown went smoothly, and usual lessons have resumed.”
A worker at a local business told the Herald he had heard an alarm ringing at the school and a helicopter was hovering overhead, though he could not see any police officers at the scene.