The violence erupting in Hong Kong amid what had so far been peaceful pro-democracy protests is being carried out by criminal gangs controlled by China, according to Hong Kong politicians and media sources.

If true, this would mark a new, potentially more violent phase in a story that has already attracted global attention.

Violence broke out for the first time in Hong Kong on Friday after several days of massive–but peaceful–marches that have riveted world attention on the former British colony. The New York Times reports that people attacking the peaceful demonstrators even groped and sexually harassed young female students. The leaders of the protests accused police of standing by and doing nothing.

Some press reports said the violence was carried out by residents who, tired of protesters who had encamped overnight in a part of Hong Kong called Mong Kok, had taken matters into their own hands and started tearing down tents.

Local Chinese journalists who cover Hong Kong’s criminal underworld say, however, that they have identified among the attackers well-known members of the 14K gang who are wearing surgical masks. “Beijing’s call went out for the Triads to come out,” said a Hong Kong newspaper executive over the phone.

The criminal Triads are controlled by interests in mainland China. Kevin Lau, a former editor of top Hong Kong newspaper Ming Pao, was attacked and nearly killed by knife-wielding triad members in February, in an attack that shook Hong Kong.

The Wall Street Journal also reported:

The government and police believe that the violence at Mong Kok is being carried out by triad gangs, according to a person familiar with the matter. “They deliberately attacked the peaceful protesters,” the person said.

Meanwhile, Reuters reported that the students were taunted with anti-Christian statements, as many of them are Christian, and with shouts of “Garbage! Garbage.” The news agency also said “Several younger men—one covered in tattoos, often a sign of Triad gang affiliation—tried to force the students to raise their arms in a gesture of submission.”

Such reports, if true, indicate that we’re entering a new phase of the struggle, and a much more dangerous one at that.

China’s communist leaders have faced a dilemma over the past week. They have made clear they will not give in to the protesters’ demands to allow Hong Kongers to freely elect their own chief executive in 2017, but they also wouldn’t want to violently suppress a peaceful protest in Hong Kong as they did in 1989 in Beijing’s Tiananmen Square. If widespread violence erupts, however, the picture changes.

Leaders in Beijing’ must be made aware that Triad violence will draw a stark contrast between criminals on one side and peaceful students demanding liberty on the other. In the situation leads to a broader crackdown, the blame will be widely attributed to Beijing, and even a White House and State Department as reluctant to speak out as this one will likely grab their megaphones.

Through the group’s official Twitter feed , protest leaders Benny Tai and Joshua Wong called on the Mong Kok protesters to leave Mong Kok and another part of the city called Causeway Bay and “continue peaceful struggle in Admiralty,” which is near Hong Kong’s financial center. Tai said he, too, suspected the Triads to be behind the attacks.

This is a wise move. It is unlikely that Triads will move into Central or other parts of Hong Kong where they will be conspicuous.