A couple has been charged after allegedly making a crude home-made bomb and leaving it in a car at a Queensland shopping centre.

The device was detected after Ipswich City Council staff monitoring CCTV footage early on Monday morning spotted two people allegedly acting suspiciously in a carpark at Redbank Plaza, west of Brisbane.

The bomb squad was called in and a 100-metre exclusion zone put in place around the car.

Police spent the day trawling through the couple's social media accounts after they were taken into custody at the scene.

Officers searched a 37-year-old Camira man's property on Monday afternoon and found two more explosive devices, which were dismantled by specialist police.

Police said they also uncovered a firearm and dangerous drugs.

The man was charged with two counts each of manufacturing and possessing explosives, and one count of possessing dangerous goods.

He also faces a string of other charges including stealing, receiving tainted property and possessing dangerous drugs.

The area was blocked off while bomb squad officers investigated. ( ABC News )

A 31-year-old Capalaba woman was also charged with possessing dangerous goods, fraud, forgery and stealing.

The couple are due to appear in Ipswich Magistrates Court on Tuesday morning.

Journalists at the scene asked Senior Sergeant Gareth James if the couple had any intention of exploding the device.

"I do not know what gain they could have from exploding it in a car park," he said.

"The shopping centre itself was not actually open at the time so we believe they were just parked here.

"It was certainly portable, too early to speculate on what their intentions were.

"We do not want to cause panic out there."

Senior Sergeant Gareth James said the device was hidden inside a cardboard box.

"At this stage all I can say is it was a fairly large glass jar which contained a substance," he said.

"Not fertiliser, there was a liquid in it of an explosive nature which also had a few other components which I won't go into."

Asked if there was a detonator, he said: "I will not say at this stage."

But he admitted it was more advanced than a Molotov cocktail.

"This was not a hoax," he said.

Police are on high alert ahead of the Commonwealth Games which begin on Wednesday on the Gold Coast.