The local government of Zhenxiong county, Yunnan Province, confirmed on Monday that 39 detainees, all drug addicts, managed to break out of a local detention center on April 6.

Of the 39 who escaped the detention center, 12 have returned after being persuaded to give themselves up or were intercepted by officials, said the local government, adding that they are still searching for the remaining detainees.

The case was first exposed just hours after the prison break in a post on tianya.cn, a popular online forum, by a 60-year-old local resident who told the Global Times Monday that his source was a police insider.

Zhao Zexuan wrote in his post that three guards failed to notice the detainees flee during their morning exercise period.

Zhao's post surmised that the detainees would not have been able to escape if any of the three layers of security doors had been locked. His conclusion aroused heated discussion online with some netizens ridiculing the guards and the detention center. One netizen said sarcastically that before the center hires new guards it should ensure they know how to lock a door.

Local authorities say the guards who neglected their duty have been suspended.

Zhao removed the post after local police demanded it be deleted. "They called and asked me to cooperate and support their work," said Zhao.

"Perhaps we have seen many criminal cases around here and we are used to it," Zhao told the Global Times, adding that most local residents remained calm after the mass escape.

A police officer at the county's public security bureau who asked not be named told the Global Times that the fugitives are petty drug addicts who have been detained but were never convicted of a criminal offense. "It doesn't necessarily mean they are dangerous. In fact, we have already helped many of them get over their addiction to drugs."

Wang Yong, a press officer with the local public security bureau, said the case is still under investigation.