Hong Kong (CNN) -- A huge manhunt involving soldiers and police is underway in China for an elusive armed robber who is thought to be behind a string of murders dating back to 2004.
The search for 42-year-old Zhou Kehua -- one of the country's most wanted criminals -- is focused on the southwestern city of Chongqing, China's biggest metropolis, after a woman was shot dead and two others injured on Friday morning outside a bank during an attempted robbery, the state-run Xinhua news agency reported.
Later that day, local police reported that a railway policeman was killed while in pursuit of a man believed to be Zhou -- his tenth victim in eight years following a series of robberies in Chongqing, Nanjing and Changsha.
All his victims were shot in the head, according to media reports, while police say he targeted people withdrawing money from banks.
Chongqing authorities recalled officers on vacation as they launched a full-scale search for the fugitive in mountainous areas around the city, Xinhua said. Police and military units from Hunan and Jiangsu provinces were also mobilized.
The search uncovered a cave that Zhou is believed to have stayed in, China Daily reported. Inside were two cigarette cases, a T-shirt and human waste, the report added. Police have said Zhou is an expert at survival in the wild, though there is no record of him serving in the military.
According to China Daily, the Ministry of Public Security has classified Zhou as a "class-A" suspect, with a total 5.4 million yuan (US$849,000) in rewards being offered for information leading to his capture.
A huge -- but ultimately fruitless -- search for Zhou was carried out in January this year after he allegedly shot and robbed a man who had just withdrawn 200,000 yuan ($31,700) from a bank in Nanjing before fleeing in a car.
Nanjing Public Security Bureau's Xuanwu district office told CNN at the time that more than 80,000 police officers took part in the manhunt. It also published two video clips online of the suspect escaping the scene.
Authorities have warned people against attempting to confront Zhou as he is considered "ruthless and highly dangerous," Xinhua said.
CNN's Dayu Zhang contributed to this report.