Chinese netizens have expressed fury over a variety of reports that they claim show preferential treatment for Muslims.
Online attacks on Chinese Muslim minorities have surged in recent years, with commenters directing angry screeds at both the Hui and the Uighur minority groups in the country's north and far west.
The alleged row that triggered the latest flood of invective took place in the city of Tangshan in northern China's Hebei province on Monday.
According to unconfirmed reports, a group of Hui protesters clashed with police who were carrying shields and wearing uniforms that suggested they were part of a SWAT team, according to online videos.
In the clips filmed at night, the protesters appeared to punch their arms in the air, point their fingers and tell police to "kneel down".
It was unclear whether one of the protesters threw a rock at the police, as was alleged in a report by the state-run Global Times.
The newspaper also quoted a Tangshan government employee as saying that "someone was beaten", without giving further details.
In response to the reports, Chinese internet users directed a flood of abuse at the official social media account of the city's public security bureau, accusing them of putting the interests of Muslims over those of the majority Han ethnic group.
"How can people ignore the law and police fail to act? What kind of place is this for Han Chinese? It is for minorities only!" one commenter wrote.
The commenters accused authorities of being overly lenient toward "violent" Muslim minorities and demanded swift punishment, in remarks that remained visible on Wednesday.
But elsewhere, searches for the term "Muslim Tangshan" and related phrases were blocked, with a message stating that the content violated community guidelines.
Calls to the Tangshan public security bureau went unanswered Wednesday.
In recent months, Chinese netizens have expressed fury over a variety of reports that they claim show preferential treatment for Muslims.
In July, an announcement by a popular food delivery app that it would start offering halal packaging provoked an explosive reaction from Internet users who complained of "positive discrimination".
But the situation of Chinese Muslims is precarious, with Uighurs in particular coming under increasingly strict curbs on their religious freedoms following a series of deadly attacks across the country.
Northern China's Hui Muslims, however, are mostly free to practise their religion.
China's officially atheist Communist authorities are wary of any organised movements outside their control, including religious ones, and analysts say controls over such groups have tightened under President Xi Jinping.