James William Shearer, 26, was in police custody in the hospital's emergency department on Wednesday after he allegedly crashed a stolen car on Yamba Drive, causing serious injury to two people.

It's alleged that while in the hospital, Mr Shearer took a police officer's Glock pistol and fired it several times.

But outside court on Thursday, solicitor Paul Edmonds said his client "strenuously" denied the allegations of attempted murder.

"I would suggest that it is entirely possible that the attempt murder charges have been an overreaction to circumstances that occurred in the Canberra Hospital last night," Mr Edmonds said.

"And those charges will not be able to be proven against my client."

Mr Shearer appeared in the ACT Magistrates Court on Thursday in handcuffs, a navy forensic suit and barefoot.

There was a strong smell of disinfectant.

The Chisholm man's face was bruised and grazed, he struggled to walk or maintain control of his expressions, and he was supported by corrections officers to a chair at the bar table onto which he slumped his head.

Chief Magistrate Lorraine Walker read the 10 charges to him.

He faces two counts of attempted murder, assault occasioning actual bodily harm, discharging a firearm endangering life and attempt to escape from custody or arrest in relation to the hospital incident.

In relation to the alleged car crashes, Mr Shearer is charged with two counts of culpable driving causing grievous bodily harm, attempted theft, driving a car without consent and unlicensed driving.

"Your Honour, I do have a licence," Mr Shearer said, speaking for the first time.

Mr Shearer pleaded not guilty to charges of attempted murder, Mr Edmonds told the court.

He did not enter pleas on the remaining charges. He also did not apply for bail and was remanded in custody.

Outside court, Mr Edmonds said his client “strenuously” denied the allegations of attempted murder.

He said they would wait for the brief of evidence in relation to pleas on the remaining charges.

On his client’s condition, Mr Edmonds said Mr Shearer was sedated while in hospital. He described his client as quite unwell, and earlier in court said the man was in a "lot of pain".

"It's unclear exactly what medication has been provided to him, but certainly he is quite unwell at the moment and will need to receive further medical treatment.

"The full extent of those injuries are yet to be determined, x-rays will need to be carried out I suspect at the Canberra Hospital later today.

"But the police allegations include that Mr Shearer was involved in a number of serious car accidents prior to the alleged shooting taking place at the hospital last night.”

Mr Edmonds said Mr Shearer would apply for bail at a later date.

The case will otherwise return to court on August 10.

The hospital's emergency department went into lockdown after the incident, in which one witness reported hearing people rushing down a hallway as about five shots rang out.

Police said officers disarmed and restrained Mr Shearer, with no members of the public or hospital staff injured.

They would not confirm reports a Taser had been used to subdue Mr Shearer.

Acting Superintendent Marcus Boorman told media outside the hospital that it was too soon to say exactly how Mr Shearer allegedly came to have a police officer's gun, or whether action would be taken against the officer whose gun was taken.

"Any incident of this nature is concerning," he said.

"We will obviously look into all our procedures, but it's too early to speculate.

"It would be inappropriate to speculate, and at the end of the investigation, it will all be revealed."

Officers from the Australian Federal Police professional standards division were at the hospital on Wednesday night and will oversee the investigation.

Speaking outside the hospital on Wednesday night, Canberra Hospital deputy director-general Chris Bone reassured patients they should still feel safe coming to the hospital and that no level of violence in the emergency department was acceptable.

The incident caused minor damage to parts of the emergency department, which has been cordoned off for repair work that was due to start on Thursday afternoon.

On Thursday morning, ACT Health said the emergency department remained operational, but anyone with non-life or limb threatening injuries was asked to consider alternative treatment options.