Dressed in a black suit and black tie, Hong Kong Chief Secretary for Administration Henry Tang placed white wreaths on the coffins with relatives of the victims, while two musicians played bagpipes in the background.
Hong Kong has been shaken by the bloody conclusion to Monday's hostage standoff in the Philippine capital in which an ex-policeman held a busload of Hong Kong tourists at gunpoint in a bid to win his job back before opening fire on the captives.
Outraged residents of this wealthy, low-crime territory have accused the Philippine government of botching negotiations with the hostage-taker and the rescue operation.
Philippine President Benigno Aquino III, facing his first major crisis since taking office on June 30, declared Wednesday a national day of mourning in solidarity with the people of Hong Kong. Flags were lowered at government offices and embassies.
China demanded a full investigation. The Chinese ambassador visited Aquino on Tuesday, and the president said he talked on the phone with Hong Kong leader Donald Tsang. Aquino said he "expressed our sorrow and grief ... and we begged for their understanding."
Philippine Interior Secretary Jessie Robredo, who is in charge of the national police, has acknowledged there were problems with how the crisis was handled, including inadequacies in preparation, equipment and training.
Manila Police Chief Rodolfo Magtibay took leave and four leaders of the assault team were relieved pending an investigation. The firearms used by 200 police commandos will be subjected to ballistic tests to determine if some of the hostages were hit by police gunfire, officials said.