A PARTY popper may have been responsible for an explosion at a construction site in West Ipswich this morning.

Witnesses alerted police after they heard a bang near the construction site of a new Bunnings store on the corner of Clay and Brisbane streets about 6.00am.

Police declared an emergency situation under the Public Safety Preservation Act (PSPA) at 11.00am but it was later revoked at 12.00pm.

A police spokesman said the device appears to be a party popper connected to a piece of fishing line attached to the gate, designed to go off when someone tried to enter the work site through the fence.

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Officers have sent what remains of the device away for further testing but early reports suggest it may have been a prank or protest against the workers in the area.

District Duty Officer, Senior Sergeant Robbie Goodger said police were still treating the situation seriously until officers had been unable to determine the device's intent.

"We always take these things very serious and thoroughly investigate each claim to ensure the public's safety," he said.

"It was pretty hectic for a while but we were able to bring everything under control and assess the threat very quickly."

Four police crews and an EORT robot bomb squad helped investigators retrieve the device and lock down the area.

Ipswich mayor Paul Pisasale says police told him the device was a party popper attached to fishing line and the "explosion" was more of a loud bang.

"They think it was either one employee trying to have a joke with another, or one of the neighbours," Mr Pisasale told AAP.

A police spokeswoman said officers couldn't determine on site whether the device was explosive, so they blew it up as a precaution.

The scare came just a week after an Ipswich boy had both his hands blown off after picking up a explosive device made out of a golf ball.

with AAP

Originally published as Bomb squad called as party popper goes off