Police are questioning the alleged killers of a multi-millionaire who was stabbed to death in an apparent botched kidnapping.

Haidian district police said four men killed the entrepreneur, who had a net worth of 100 million yuan, on Thursday afternoon. Investigators believe the men were trying to kidnap him from the parking lot of a Haidian shopping mall at the time.

One suspect is believed to have killed himself on the spot when the bid failed. Three other men were arrested within 24 hours of the murder.

The victim was a 41-year-old entrepreneur named Hu Zhong who was chairman of Paper Tiger, a comprehensive cultural company founded in 1999.

Paper Tiger has grown quickly since 2004 and has in excess of 100 million yuan in annual sales and more than 60 chain stores in Beijing and Shanghai.

Its flagship store, which comprises the biggest cultural and entertainment square in the city, occupies nearly 10,000 sq m in Golden Resource New Yansha Mall, which was once the largest shopping mall in Asia.

The store was operating normally on Sunday.

"We were not officially told of our boss' death until this morning," said a saleswoman in her 20s who asked to remain anonymous.

She said Hu was nice to employees and always read in the company's book bar when he had time.

Jiang Lu, brand manager with Paper Tiger, said on Sunday: "It was shocking news to all of us. He was such a nice guy and was very popular with his peers in the publishing industry.

"We set up a mourning hall in our company just a few hours ago and more than 200 people have already offered their condolences."

She said Paper Tiger's business had not been affected by the killing and another general manager had taken on Hu's duties.

Many netizens were also expressing their sorrow online through messages and micro-blogs.

Others used the Internet to talk about their safety concerns about parking lots, especially free ones provided by shopping malls.

"I have always liked the mall's free parking lot with more than 10,000 parking spaces, but is it less safe because it's free?" asked a netizen named Xi Ming.

Huang Yizhi, a lawyer with Beijing Ruifeng Law Firm,

said the administration office of parking lots are responsible for customers' safety, no matter whether the lots are free or not.

"However, the responsibility is not limitless," she said.

"Security guards are not private body guards. It requires detailed analysis of whether guards from the parking lot had fulfilled their role to decide whether they should take partial responsibility for Hu's death."

So far, police have not spoken in detail about the case, pointing out that it is still under investigation.