"We are on strike, a permanent strike," Willie Madisha, the president of the Congress of South African Trade Unions, told a massive rally that brought downtown Johannesburg to a standstill.
"Until such time as we get 12 percent we are not going back."
He vowed to try to extend the strike to the mining, metal workers, and transport sectors and bring the country to its knees.
Many schools throughout the country were closed for the day yesterday, with principals telling pupils in advance not to bother showing up.
Most airports were running normally, but some prisons were operating with a skeleton staff.
Police are classed as "essential workers" and so banned from striking. But they share the same grievances.
Vukile Pambo, a police union official, scornfully said that government ministers would be able to "sleep very nice" because of the police.
"You will see some of us working today, but you will not see that forever. We are not government dogs," he told the Johannesburg demonstration.
The strike was largely peaceful. Police fired stun grenades to disperse around 500 protesters who were preventing doctors entering one of Cape Town's largest hospitals, the South African Press Association said.
But there were no immediate reports of other incidents, in contrast to strikes by security guards and transport workers last year which ended in riots.
In many towns, motorists honked their horns to support the teachers and nurses, who say their existing wages don't even cover basic housing, food, education, and transport costs.
They are particularly angered that top government officials were awarded increases of more than 50 percent earlier this year.
In hospitals, there was sympathy for striking nurses.
"I think they are right to strike," said Joan Grant, an elderly patient who was waiting for her twice-yearly appointment to check her medication and said she risked another six-month wait if it was canceled.
Dikgang Simomosieleng waited hours with his elderly mother to meet a doctor at Johannesburg General Hospital.
"The government should give them their 12 percent," he said.
