The March 13 statement said that personnel found to have violated laws will be "resolutely punished."
"On March 12, 2017, a suspect died while our bureau's criminal investigation squad was handling a case of a telecommunications fraud ring," Wenxian county police said on its Twitter-like Weibo account.
"The People's Police handling the case are suspected of using torture to extract confessions and collect evidence," the March 13 statement said, adding that personnel found to have violated laws will be "resolutely punished."
The notice was viewed online more than 13 million times, Global Times newspaper noted Tuesday, with most Weibo commenters praising the bureau for its openness about misconduct.
Chinese news outlet Paper.cn cited the bureau as saying that the officers have been suspended from duty and their cases were transferred to the local procuratorate for investigation.
It is unclear whether the suspect was brought to a hospital for treatment or died in a detention centre. The bureau's public affairs department did not answer calls from AFP on Tuesday.
"This is not the first time Chinese police admitted use of torture, but it is the first time the police released such information on a public network," Chen Guangzhong of the China University of Political Science and Law told AFP.
"This seems to be a new communication tactic," said Jeremy Daum of Yale Law School's Paul Tsai China Center in Beijing.
"If people believe that the situation is being reviewed openly in accordance with law and handled justly, they are more likely to wait and see what happens rather than take their concerns to the streets," Daum told AFP.
Chinese courts have a conviction rate of 99.92 percent, and concerns over wrongful verdicts are fuelled by police reliance on forced confessions and the lack of effective defence in criminal trials.
Overseas rights groups say China executes more people than any other country, but Beijing does not give figures on the death penalty, regarding the statistics as state secrets.
In December 2016, China's top court cleared a man executed 21 years ago for murder, citing insufficient evidence in the original trial.
While the "landmark" verdict was a sign that China's judicial system has improved since the 1990s, observers say many problems remain unaddressed.