Police have been asked to step up patrols around town following a brutal knife attack that left two women dead, Chief Executive John Lee said on Saturday, although he stressed that Hong Kong is considered a safe place.

The request made by the city's leader was among four initiatives to make members of the public feel at ease.

Lee told reporters that the government will review and improve treatment and rehabilitation services for those who are mentally ill, hold meetings as soon as possible to draw up a more comprehensive and safer response to deal with mental health issues in the SAR, as well as strengthen support services in the community.

He also praised those who had helped out during the incident at Plaza Hollywood in Diamond Hill, and said that law enforcement officers would continue to uphold law and order in the city.

"We understand people, especially after watching online videos, would be emotional. We understand that, so we stress that Hong Kong is still a safe city," Lee said.

Asked if the Happy Hong Kong marketplace should be put on hold, Lee said: "When we see certain things that we don't wish to happen occur, we will feel unease and be affected.

"But more importantly, we must face unfortunate events that we do not want to see happen. We must help each other and be positive, to continue to live normally. This is important in balancing our mental well-being."

Health secretary Lo Chung-mau, for his part, said it was "totally correct" for passers-by to lend a helping hand to rescue the attacked victims.

But the minister expressed sadness that medics could not help the two victims despite their best efforts, noting that the injuries suffered by the women were very serious.

He also called for understanding: "I hope the public do not label people who need assistance for their mental health. I hope everyone can support them, especially by encouraging them to seek help and treatment, so that they could be healthy again."

Chairman of the Equal Opportunities Commission Ricky Chu appealed to members of the public to deal with the incident in an objective and calm manner, and separate what had happened on Friday from mental health issues.

He added that there is no direct correlation between mental illness and violence.