The DAB's Chan Wing-kwong, Adrian Ho of the New People's Party, Shang Hailong from an artificial intelligence firm and Chinese University engineering scholar William Wong were on Sunday elected Legislative Council members in a by-election described by the government as fair, honest and efficient.

Six candidates competed for four Legco seats left vacant after Horace Cheung, Alice Mak, Sun Dong and Nelson Lam joined Chief Executive John Lee's administration in July.

Voting took place between 9am and 11.30am. Turnout was 90.7 percent, with 1,307 of 1,441 Election Committee members casting their votes.

Chan was the top vote-winner, receiving 1,028 out of 1,307 ballots cast.

Speaking after the results were announced, the DAB member and Chinese medicine practitioner said he hopes to promote traditional Chinese medicine in the SAR.

Wong, from Chinese University, said he vows to build a hub for innovation and technology here.

"I have always been wanting Hong Kong to become an innovation and technology hub, and I have been working very hard on it. I'm very glad that I'm elected, as such, I'm given another platform to push what I believe [in]," he said.

Shang, who's general manager of SenseTime Hong Kong, echoed Wong's views.

"I want to use advanced technology to engage all kinds of industries, that's my priority," he said.

Gary Wong, a member of the Chinese Association of Hong Kong and Macau Studies, and Lee Kwong-yu from the Federation of Trade Unions failed to win a seat.

David Lok, chairman of the Electoral Affairs Commission, said the election process was smooth. He said it took about an hour to complete the counting of votes and announce the results.

Lok also said there had been six complaints about the election so far, and stressed there are certain guidelines candidates have to comply with. "Of course we have set out regulations and guidelines requiring candidates to comply with application of the election advertisements, so I think these candidates will have to comply."

Secretary for Constitutional and Mainland Affairs Erick Tsang said in a statement that the election was held "in a fair, just and honest manner". He also said authorities had implemented efficient and user-friendly measures, such as setting up special queues for those in need, to facilitate voting by Election Committee members.

Chief Executive John Lee congratulated the by-election winners. Lee will administer their oath-taking in a ceremony on Monday.