Hundreds of ambulance officers and firefighters have rallied in Adelaide calling for more funding, warning lives are at risk without extra resources.
Both groups have been engaged in prolonged disputes with the government over staff and equipment levels.
The rally gathered in Victoria Square on Thursday before marching to parliament house.
United Firefighters Union state secretary Max Adlam told the crowd of a dire situation, with fire trucks continually breaking down, few spare parts and a "skeletonised" engineering division.
She said their calls were not about increased pay, but for the safety of the public and the welfare of emergency service workers.
"It's about the frustration and despair our members are feeling as they try to access the things they need to do their jobs," Ms Adlam said.
"Our people do long hours, they do shift work continually, they study, they train hard and they're dedicated.
"Despite all the challenges they love their jobs."
Ambulance Employees' Association secretary Phil Palmer told protesters the state government was playing a "dangerous game of Russian roulette" with public safety in its refusal to provide adequate resources.
Mr Palmer said the association had been warning the government for years that a crisis situation was emerging.
He recently told a parliamentary committee that a royal commission into the funding, staffing and operation of the ambulance service was needed.
He said some calls for ambulances were being left unattended putting lives at risk, crews were being forced to ramp outside hospital emergency departments, and low-priority patients made to wait more than 12 hours in the face of ever-increasing demand.
"There is not a corner of the ambulance service that is not under pressure," Mr Palmer told the committee last month.
"It is the worst it's ever been. I've been doing this job 34 years and have never seen it this bad."
The state government said it was committed to properly resourced emergency services and resolving current disputes.
It recently offered to employ an extra 50 ambulance officers on top of what it said were hundreds recruited since the last state election.
It also promised to recruit even more officers once enterprise agreement negotiations had been finalised.
But it said it also needed reforms, including revisions to outdated rostering arrangements and an end to tiring 12-hour shifts.
"No amount of industrial action will actually help resolve these issues," Treasurer Rob Lucas said.
"The only way to resolve any kind of dispute is for both parties to compromise and the government is, once again, calling on the union to compromise for the benefit of hardworking paramedics and all South Australians who rely on them."