A 21-year-old man has been charged with murder following the fatal stabbing of a young ambulance paramedic in Sydney’s southwest.

Named by media outlets as Steven Tougher, the 29-year-old father of one was stabbed outside Campbelltown McDonald’s while he and a workmate took a break towards the end of their night shift about 5.30am on Friday.

The colleague activated a duress alarm, sparking a police response in which a younger man wielding a knife was tasered and arrested.

Homicide detectives later charged the 21-year-old man with murder.

He has been refused bail to appear at Parramatta Local Court on Saturday. 

The victim, who had been working for the ambulance service for about a year, was assisted by witnesses at the scene but died shortly after arriving at Liverpool Hospital.

“The surgeons … worked valiantly, albeit futile in this instance, to support our colleague,” NSW Ambulance Commissioner Dominic Morgan said.

The slain man’s father said his son always wanted to be a paramedic and had just been posted to southwest Sydney, Dr Morgan said.

“I’ve met with the family and as you can imagine personally, it’s very difficult to process.”

A GoFundMe page set up on Friday afternoon sought support for the paramedic’s partner Madison who is expecting a second child.

“Madison is due to have her second child in a few short weeks,” the page description read.

It is understood the couple intended raising their family in southwestern Sydney after he recently landed a posting in the area.