BEIJING, June 9 -- Eight police officers are being investigated on suspicion of turning a blind eye to a gambling den in southwest China's Guizhou Province.

The gambling site, a simple tent in a flat area in mountains in Guizhou's Kaili City, was exposed when an explosion killed 15 people there in January. Most victims were gamblers.

The officers under investigation included Liu Jianjun and He Changqing, Kaili deputy police chiefs, said a Monday statement by the Supreme People's Procuratorate (SPP).

They are suspected of knowingly harboring a gambling den and protecting the organizers, which led to the fatal explosion, the statement said.

They have been put under coercive measures. According to China's criminal procedure law, the coercive measures include arrest, bail and residential surveillance. The SPP did not specify which measures have been taken in this case.