A FATHER of three paced back and forth, his gun trained on his own head, shadowed by police officers whose weapons followed his every move.

Guns drawn, the officers stood in the open of Brisbane's Queen Street Mall as he shouted at them from just a few metres away to shoot him.

The man screamed for his children, one hand heavily bandaged after a bizarre incident in January.

Minutes earlier, shortly after 11am, a team of two plainclothes police and a bicycle officer had finally approached the man after following him through the mall.

He had been acting suspiciously, so they stopped him outside the Myer Centre and asked to see some identification.

"Police doing proactive patrols in the Queen St Mall had asked the man for identification," Detective Chief Superintendent Mark Ainsworth said.

"He reached in his pocket to get the ID - and pulled out the firearm. They were (standing) very close."

No time for fear: Policeman calm in face of danger.

The officers drew their own guns and shouted at the man, 34, to drop his weapon.

Spotting the guns, shoppers ran shrieking from one of the country's busiest shopping strips.

"I was walking next to the man outside the Myer Centre," one witness said.

"He pulled out a gun but he was surrounded by two undercover cops. They pulled out their guns then too and they shouted 'gun, gun, gun'."

It took just five minutes to clear the thousands of shoppers from Queen Street Mall as dozens of police converged on the strip, ordering people to evacuate and locking down shops and businesses.

In Hungry Jacks, diners were ordered downstairs by police who told them a gunman was on the loose.

Staff and patrons in clothing store Cotton On hid in a rear storage room.

media_camera The Queen Street Mall is in lockdown following reports of a man with a gun in the mall. Pictured is the alleged gunman.

"He was going around everywhere and holding the gun to his neck out of the front of our store," said a shop worker, who spent more than three hours locked inside Latin Clothing Company, said.

The man swore at police and screamed at them to shoot him.

He screamed for his children as he paced the mall, stopping at one point to use a pay phone.

"He was saying he just wanted to see his kids, that's all he wanted to do and they were saying 'we'll get your kids for you, just put the gun down, please can you put the gun down'," the shop worker said.

At one point the gunman asked for a cigarette and police obliged after finding a packet inside a locked down store.

By noon, heavily armed Special Emergency Response Team officers had arrived, moving towards the man as he paced the mall.

Stranded shoppers heard shots as officers fired non-lethal bean bag rounds at the gunman, wounding him in the shoulder and leg.

"The guy got shot (and) we went to the windows to have a look and he was just on the floor with blood on his shoulder and his leg," the shop worker said.

Another witness was locked in Xpress Money when he heard the shots.

"He was saying to police, 'shoot me in my head'," he said.

"He was shot on his shoulder, I could see blood on his shoulder. Then the police caught him."

Chief Supt Ainsworth praised the efforts of several officers who, out in the open, held the man at bay as he brandished his gun.

"You really have to acknowledge the calmness of the police officers," he said.

"(Their response) highlighted the professionalism of the police and demonstrates they did a magnificent job."

media_camera Heavily armed SERT police officers arrive at the Queen Street Mall in Brisbane's CBD.

The man was taken to hospital with minor injuries and was expected to be charged overnight.

Reporting by Kate Kyriacou, Thomas Chamberlin, Rikki-Lee Arnold, Mark Solomons, Felicity Sheppard