The workers turned violent, pelting stones at the company premises. They shouted slogans accusing a contractor, Harender Singh, of assaulting them with scissors. They demanded his arrest.
Fearing trouble, the company asked the workers to vacate the company premises.
When a small police forced the site, the workers set fire to police vehicles including one belonging to Assistant Commissioner Ravinder Tomar.
When the fire brigade rushed to the site, one of its vehicles was also torched.
“Our men managed to save their lives,” fire officer I.S. Kayshap told IANS.
More than 35 vehicles, including 20 two-wheelers, were set ablaze in the violence.
Police have registered a criminal case against more that 1,000 people and detained some workers, police officer Narender Kumar said.