BEIJING — The photograph is so graphic that it appears cartoonish at first glance.

A man lies on a road with his eyes closed, blood streaming from his half-open mouth, his torso completely crushed under the large tire of a red truck. One arm reaches out from beneath the tire. His shoulder is a bloody pile of flesh. His head is no longer attached to the flattened spinal cord.

The man in the photograph, Qian Yunhui, 53, has become the latest Internet sensation in China, as thousands of people viewing the image online since the weekend have accused government officials of gruesomely killing Mr. Qian to silence his six-year campaign to protect fellow villagers in a land dispute. Illegal land seizures by officials are common in China, but the horrific photographs of Mr. Qian’s death on Saturday have ignited widespread fury, forcing local officials to offer explanations in a news conference.

It is the latest in a string of cases in which anger against the government has been fanned by the lightning-fast spread of information online. In late October, the son of a deputy police chief in central China drunkenly drove his car into two college students, killing one and injuring another. His parting phrase as he drove away from the scene of the crime — “Sue me if you dare, my father is Li Gang!” — has since become a byword for official corruption and nepotism.