The man who sparked a three-hour lockdown in Mackay's CBD in north Queensland yesterday, had two high-powered rifles, including one fitted with a scope and tripod, police will allege.

Troy Dean Sprigg, 29, from Sarina south of Mackay, faced Mackay Magistrates today court on a string of charges including going armed so as to cause fear, dangerous conduct with a weapon and unlawful possession of a weapon.

The man eventually surrendered to police and was arrested about 8:00pm after an emergency was declared shortly after 5:30pm.

Mackay superintendent Bruce McNab said police believed the man fired between four and eight rounds.

"At this stage the information is he was firing into the air but we have found rounds strikes on a building so whether that was intentional or not is not clear," Superintendent McNab said.

"This is two very high-powered rifles, one of them with a scope and a tripod, and they had the potential to cause serious injuries to people if it hit them — and because of the size of the rounds they could travel quite a distance."

No-one was injured during the incident, but Mr McNab said it was very concerning.

"It's one of our worst nightmares to have a person armed in a large population in town," he said.

"We're still investigating what his actual movements were before firing the shots … we know that there was a verbal altercation or interaction between him and some other people at the Showbar."

"Mackay people responded very well, people locked down in place, they followed police direction and they moved very quickly."

'I just froze,' witness says

Business owner, John Platts, said he was standing just five metres from the man when he allegedly fired shots into the air.

Mr Platts said he was walking to the local corner store, when he heard a large "bang".

Mackay business owner John Platts said the alleged gunman was metres from him. ( ABC News: Melissa Maddison )

"I felt the boom, it was incredible," Mr Platts said.

"I thought it must have been a tyre blowing up."

He said when he turned around, the man was standing near him in the street.

"I just froze, I couldn't move, it was a bit of a blur at first, really really scary," he said

"The guy behind me was yelling at me to get going and move or hide and I just couldn't, eventually I unfroze and I ran to the shop and hid."

Police escort the man into Mackay Base Hospital after he surrendered on Wednesday night. ( ABC News: Tara Cassidy )

Mr Sprigg's lawyer did not make an application for bail in the Mackay Magistrates Court and he was remanded in custody.

Police said further charges were likely as the investigation continued.

They are appealing for witnesses or anyone with dash-cam footage or CCTV to contact police.

Earlier, Detective Inspector Brendan Smith said Mr Sprigg was taken to hospital for an assessment after he surrendered to officers.

"A number of shots were fired earlier in the day and we believe that was his attempt to draw attention to himself," he said.