Updated

Students and alumni of several Chinese universities are sounding the alarm over the apparent detention of more than a dozen young labor activists who have been missing since the weekend.

Three recent graduates of the elite Peking University have been taken away by authorities, the Jasic Workers Support Group said in a statement late Tuesday. According to the group, eyewitnesses saw one person being "kidnapped" from the Beijing campus, while others in Shenzhen, Guangzhou and Shanghai also disappeared last Friday.

They were involved in a coalition, led by young Marxist activists, that was founded this summer to show solidarity with factory workers at Jasic Technology, a welding equipment manufacturer in southern China.

Activists in China are routinely "disappeared" by authorities working for the ruling Communist Party, which is wary of collective action and potential threats to its authority. The young Marxists, however, are an unusual target because they espouse the same values — socialism, workers' rights and Marxist ideology — for which the party has itself advocated.

The sudden disappearances all occurred at around 9 p.m. on Friday, the Jasic Workers Support Group said. Three others in Wuhan, including one factory worker, were taken away by police on Sunday, though one was released early the next day.

Peking University students and alumni have expressed alarm after students published accounts online saying that they were beaten on campus by unidentified men who forced a recent graduate named Zhang Shengye into a car on Friday evening.

One fourth-year history student, writing on the Jasic Workers Support Group's website, said he was thrown to the ground outside of a lecture hall by five people dressed in black.

When he asked them who they were, he recalled, one swore at him and yelled, "If you keep yelling, we'll keep hitting you!" Shortly afterward, a tall, burly man started kicking his head.

The student said he then saw that someone was being dragged into a car that swiftly drove away.

The student who wrote this account could not be reached on Wednesday. Members of the Jasic Workers Support Group, who spoke on condition of anonymity, said they believe he has been forced to leave campus for the time being.

On Wednesday evening, someone who identified himself as a third-year Peking University medical student said in an online post that he had a similar encounter on that same night, when people in dark clothing rushed at him and held him to the ground until he bled.

In a statement posted on an internal Peking University forum, the school's security department said the "situation" on Friday was that of a "police department lawfully taking into custody a criminal suspect ... who is not a current student, teacher or employee of the school."

A member of the security department confirmed over the phone Wednesday that the statement came from the university.