This screenshot shows a police officer sings for a woman at a police station.

A video of police officer Liang Tao singing to help calm down a mentally ill woman has gone viral online, the Chongqing Morning News reported on Wednesday.

Liang, 32, sang for two hours to a woman in a police station in Southwest China's Chongqing municipality. The woman was so pleased with the singing that, while clapping her hands, she asked Liang, "Are you a singing god?"

The video went viral online with over 700,000 clicks within 3 hours.

Liang found the woman lingering in the countryside in Chongqing on May 9. She failed to clearly give her home address, and wasn't carrying correct ID. She repeatedly said her last name was "Ka". Liang took her back to the police station for her own safety, and when she appeared nervous, he began to sing to her.

Liang was able to contact the woman's husband, Mr Ma, who confirmed that the woman, surnamed Wang, was mentally ill and arranged for her to be collected from the police station.

A grateful Ma said that Wang had become lost while he was busy outside, which has happened several times before. Wang likes songs, especially happy ones, he said.