Tens of thousands of workers turned out for the rally to protest government plans to make changes to a 2003 labor law, which businesses claim discourages investment by making it hard to fire employees. However, the demonstration turned violent after some of the protesters started setting tires on fire on a toll road near the heavily guarded parliament; police were called in to intervene.
See "Indonesian Police, Labor Protesters Clash", Irwan Firdaus, San Francisco Chronicle, May 2, 2006