The trouble started at midday when the protesters, from the SA Transport and Allied Workers Union, smashed the windows of 10 trucks, pulled drivers out of their vehicles and forced them to join the march.
"The protest turned violent on Rissik Street at about 12:20," said Metro spokesperson Chief Superintendent Wayne Minnaar.
"The protesters smashed the windscreens of trucks. The situation was tense.
"Later in the afternoon the situation had calmed. The metro police and members of the SA Police Service were keeping a close watch on the protesters at the Library Gardens."
Knobkerries and loud music on Beyers Naude
The workers are demanding an increase of 20% over the next two years and the banning of labour brokers. The Road Freight Employers' Association (RFEA) has offered 15%.
The wage talks between the unions and RFEA deadlocked in December. The unions have been issued with a strike certificate by the Commission for Conciliation, Mediation and Arbitration.
In 2009, Satawu and RFEA signed an agreement which included an 11% wage increase for all road freight industry workers across the board after workers embarked on a seven-day strike.
Satawu members who had gathered at Beyers Naude Square danced and shook knobkerries as loud music thumped around the square.
Many demonstrators drank from 2 litre cooldrink bottles and the ground around them was littered with sachets of cane, sambuca and brandy.
Cops joke with protesters
On the lawns of the square police joked and chatted with protesters, who were playing cards under a tree.
At the other end of the city centre, a separate group of about 500 protesters from the Motor Transport Workers' Union sang and danced outside the headquarters of the National Bargaining Council for the road freight industry.
Police had cordoned off the road and were maintaining a heavy presence.
A protester, who declined to be named, said the strike began at 06:00 on Sunday and would continue until the employers gave in to their demands.
"It's not a matter of 'should give in', it's a matter of 'must give in'."
A truck driver at Beyers Naude Square said he was protesting because he could hardly get by on the salary he was being paid.
65 000 workers to strike
"They are paying me less than R4 000 a month to drive a truck from 07:00 to 17:00. I cannot get by on this. They must raise our salaries by 20%," said the man who identified himself only as "Jan".
Satawu president June Dube said the road freight industry would be brought to a standstill as about 65 000 members intended joining the strike during the week.
Transport and Allied Workers' Union of SA (Tawusa) general secretary Zack Mankge said workers from other unions would join the strike on Tuesday.
"We are marching... to hand over a memorandum of demands to the National Bargaining Council for the Road Freight Industry," he said.
Mankge said Tawusa was "not aware of any violence" and that the strike would be "peaceful".
"The unions will meet with the employer on Tuesday," he said