Experts have called on netizens to be more cautious in reporting acts of extreme violence after two violent crimes on buses took place within a week, killing seven and injuring more than 20.

Four people are dead and 11 more in hospitals as of Monday in the aftermath of a multiple stabbing on Sunday in Chengdu, Sichuan province.

A man who was stabbed in a multiple attack in Chengdu is transferred to a larger hospital for treatment on Sunday night. Hua Xiaofeng / for China Daily

A man stabbed passengers on a bus and then continued his rampage after getting off in Chengdu.

Police said the man may have committed the attacks because of financial problems and the long-term stress of working away from his hometown.

Police confirmed that the suspect, surnamed Li, 41, is a native of Jintang, a suburban county under the administration of Chengdu.

Li has long worked outside his home county. He left Xichang, the capital of the Liangshan Yi autonomous prefecture in Sichuan, where he worked on Thursday evening and returned to his home in Jintang on Saturday. At noon the next day, he arrived in Chengdu.

"The man is in discord with his family over economic issues," said Xiong Dezhuang, an information officer with the city government.

Within a week, the country has witnessed two similar incidents in which suspects have stabbed innocent bystanders.

On Aug 19, Zhou Jiangbo, a 24-year-old farmer from Huangxian county, Henan province, killed three people and injured 12 on a bus in Anyang.

The deceased were a 10-month-old girl and two boys, 10 and 17 years old.

The Sunday incident in Chengdu may have been carried out in imitation of the Anyang attack, said Ma Ai, a professor of criminal psychology at China University of Political Science and Law.

Reporting on acts of extreme violence is a "double-edged sword", Ma said, explaining that reports may spark copycat attacks by people with psychological problems. But at the same time, the public needs to be kept informed of events.

"While acts of extreme violence cause great social pain, the more attention people and media attach to them, the more likely it is that they will be imitated," Ma said.

"The heavy-handed way the public called for a crackdown works in preventing imitations in a way," Ma said, "but we still don't have very good methods to prevent them."

The detailed descriptions provided by online social media may encourage copycats, said Ding Junjie, vice-president of the Communication University of China.

Some people may feel encouraged by the description of details, combined with a strong heroic tone, Ding said.

While Ding supports "enacting a law to advocate civilized dissemination" as one way of dealing with the problem, he said it will be some time before change occurs.

"We should try to solve the hidden problems, mainly social conflicts, behind the extreme violence, which come before and are the roots of the imitations," he said.

Lin Bingxian, a researcher at the China University of Political Science and Law, said the country should make mental health knowledge more accessible to citizens, especially juveniles.

"If China cannot reach the standards of having one psychiatric consultant for each 1,000 people like developed countries do, we should at least have one consultant for every 10,000 citizens," he said.

Contact the writers at huangzhiling@chinadaily.com.cn and houliqiang@chinadaily.com.cn

Xinhua contributed to this story.