A North Korean man believed to be an army deserter has been arrested and detained by Chinese authorities for allegedly killing four Chinese citizens during attempted robberies inside their homes in the border city of Helong, according to multiple media reports.

The gun-wielding North Korean man crossed the border in late December, stealing money and food before killing the Chinese nationals in Nanping in Helong in Northeastern China, located just north of the Tumen River, which has been used for years by people trying to flee North Korea, as it forms part of the boundary between China and North Korea, said South Korea's Yonhap news agency, citing a source with knowledge of the incident.

On Dec. 27, the unidentified soldier stole a pistol and broke into the home of an ethnic Korean man identified only as Xu. After murdering Xu and his wife, the suspect moved on to the neighbors' home and beat another man to death with his weapon, The Dong-A Ilbo newspaper reported. Entering a third home, the man stole 100 Chinese yuan ($16) and some food.  

Shortly after the shooting spree, Chinese police and military officials launched a manhunt. After being spotted north of the Tumen River, the suspect was shot in the stomach and is currently in a coma.

The Chinese foreign ministry has reportedly lodged a protest complaint with North Korea, a spokesperson said, declining to provide additional details. The incident, however, has not been announced by Chinese authorities and the country's state-run media organizations have also remained silent, according to BBC News.

"China's public security bureau will handle the case according to law," a ministry spokeswoman said, suggesting the suspect will be prosecuted in China rather than handed back to Pyongyang.

It is not uncommon for North Korean soldiers or citizens to cross the border into Chinese towns and attempt robberies before seeking to travel onto a third country and then into South Korea. Deemed as economic migrants, China often repatriates defectors back to the North.

Meanwhile, surveillance of the North Korea border has been increased by Chinese authorities and likely routes taken by defectors have been restricted. Since Kim Jong-un took power in 2011, even North Korea has strengthened border security to prevent defections, according to activists.