Johannesburg - More than 20 trucks were damaged, about 16 people were injured and 32 were arrested during the road freight strike which hit its fourth day on Thursday.The strike of about 65 000 workers, according to the unions, has thus far been marred by violence and intimidation.The industrial action began with a go-slow on Sunday, but workers across the country downed tools on Monday.The unions - the Transport and Allied Workers Union of SA, the Professional Transport Workers Union, the SA Transport and Allied Workers' Union, and the Motor Transport Workers Union - are demanding a 10% increase for 2011 and 10% for 2012.On Monday, four striking truck drivers were injured when police fired rubber bullets at workers during a protest march. Ten trucks were damaged.A man was reportedly hospitalised after he was pulled from his truck on the East Rand and beaten.On Tuesday, a man was beaten and hospitalised after the truck he was driving was attacked. On the same day, three trucks were burnt on Gauteng's East Rand and another man was attacked, allegedly by striking workers in Salt River in the Western Cape.On Wednesday, four taxi passengers were seriously injured when a truck crashed into their vehicle while its driver was trying to get away from strikers on the East Rand.Two trucks and a bakkie were stoned and looted, also on the East Rand.Beeld reported that two truck drivers were reportedly admitted to hospital in Mpumalanga, after being forced off the road by striking workers who assaulted them with pangas and sticks.Five trucks that were transporting chrome to Witbank were forced off the road between Breyten and Carolina by strikers in four bakkies.A truck passenger was shot in the head in KwaZulu-Natal in an incident believed to be linked to the truck drivers' pay strike. A truck driver was also stoned along the N3.Four people were arrested on Sunday for intimidation in Howick, also related to the strike.On Thursday, two trucks were burnt and a bystander beaten and robbed in Irene. Police estimated that the value of the two vehicles was R1.7m and its cargo was worth R380 000. Twenty-eight people were arrested.The countrywide strike has resulted in fuel shortages at petrol pumps throughout the week.SA Petroleum Industry Association (Sapia) executive director Avhapfani Tshifularo said reports of petrol pumps running dry were received on Thursday.He added that stations generally received their supplies later on the same day."There are still some challenges of sporadic intimidation persisting and this is causing a challenge to supply," he said."It is likely to be like this for the duration of the strike."Power supplier Eskom said it had sufficient coal supplies, with a 40-day stockpile. It had experienced some delivery challenges.On average, the parastatal received less than a third of its coal deliveries by road. It was monitoring the situation daily.Food and grocery deliveries were not severely affected. A spokesperson for Pioneer Food Group [JSE:PFG] said there were no problems to report.Pick n Pay Stores [JSE:PIK] supply chain director, Burger van der Merwe, said stores were "largely unaffected" by the strike."The company has extensive contingency plans in place to ensure that the service to our stores and customers are acceptable during the strike."Store deliveries from the company's distribution centres are unaffected, but a limited number of suppliers are finding it difficult to deliver directly to stores."Talks were continuing between the unions and the Road Freight Employers' Association (RFEA).On Thursday the RFEA increased its offer to 9%, which the PTWU found more palatable than its Wednesday offer of 8% for 2011 and the same for 2012.The RFEA had moved from 7.5%. Talks were continuing on Thursday.