Alleged cop shooter returns to hospital

First he allegedly put a pair of scissors to the throat of a female doctor.

Then he shot and wounded a police officer and a security guard.

Now he's being treated at the western Sydney hospital he allegedly terrorised.

The 39-year-old man returned to the scene after he was unable to face court in Penrith because of injuries reportedly sustained prior to the violent attack.

Terrified patients and staff inside the emergency department at Nepean Hospital watched on in horror late on Tuesday night when the 39-year-old, who once worked as a nurse at nearby Westmead Hospital, allegedly took a female doctor hostage.

"I heard a woman screaming, quite hysterically ... and then following that, there were some gunshots. What I saw was blood. Lots of blood on the floor," witness Jodie Bennett told ABC TV.

The first officer on the scene, dog squad cop Luke Warburton - who was involved in the capture of notorious criminal Malcolm Naden - was shot in the thigh after the 39-year-old allegedly grabbed a hold of his gun.

Hospital guard Barry Jennings, 48, was also injured by the same bullet.

Mr Warburton, 38, underwent emergency surgery and is recovering at the hospital in a critical but stable condition, with his wife by his side.

Mr Jennings also underwent surgery and is in a stable condition.

The 39-year-old man had been released on bail over an alleged break-and-enter just hours before Tuesday night's incidents.

He was due to face Penrith Local Court on Wednesday afternoon on a shooting with intent to kill charge but officers took him back after he was deemed medically unfit.

The incident has highlighted fears emergency departments are becoming "more and more like battlegrounds" because of an increase in ice and alcohol-fuelled violence.

Health Services Union secretary Gerard Hayes said security guards must be able to carry handcuffs or material restraints.

"We've been saying for some time to have the power to be able to restrain and detain people," he said.

"It is a crazy situation we have been advocating for many years."

NSW Health Minister Jillian Skinner said she would meet with the HSU next week.

"The security and welfare of staff and patients in our hospitals is always paramount," she said.

Acting NSW Police Commissioner Catherine Burn said police were shaken up by the event.

"We hope that the officer pulls through very, very quickly," she said.

"For everybody involved this is a very traumatic situation. And my thoughts are with the doctor as well at the moment."