HONG KONG — A lawmaker, a father, his teenage son and a woman who was too scared to show her face spoke Wednesday about an attack in a Hong Kong train station by a mob of men armed with sticks and poles. The assault on Sunday targeted people who were returning from antigovernment protests, and raised the fears of violence compounding political upheaval in the city.

Lam Cheuk-ting, a pro-democracy lawmaker who rushed to the scene of the attacks in the satellite town of Yuen Long, said blame lay with both the police, who failed to protect people, and the organized crime groups known as triads who allegedly carried out the attack.

“The police and the triads now rule Yuen Long together,” said Mr. Lam, who was beaten in the attack and required 18 stitches for cuts to his mouth. “The police allowed the triads to make plans, to prolong the attack and to beat up civilians. The police allowed these mobsters sufficient time to leave the scene.”

The mob attack has stirred fear and anger in Hong Kong. The streets of Yuen Long were desolate Monday night, with businesses closing early and residents staying home out of fear of further violence. The police have now arrested 11 men accused of being connected to the mob attack, and local news outlets have reported that some of those arrested have affiliations with two prominent triads, 14K and Wo Shing Wo.