Beijing (AP) – Police in northern China say an argument between construction workers escalated into a demolition derby-style clash of heavy machinery that left at least two bulldozers flipped over in a street. An online video shows several bulldozers ramming each other while passenger cars scurry away from the cloud of dust on Saturday. The video shows one driver running unhurt out of a toppled bulldozer, a fast-moving type also known as a wheel loader. Xu Feng, a local government spokesman in Hebei province’s Xingtang county, said Monday that the workers were from two companies competing for business, but couldn’t disclose details about arrests or injuries until an investigation concludes. China’s construction sector has fallen on hard times, with growth down by two-thirds from its peak a decade ago.