MANILA  In the face of growing Chinese anger, Philippine officials acknowledged failings in how the police handled a 12-hour hostage standoff on a tourist bus, which unfolded on live television and ended with the deaths of eight passengers from Hong Kong and the armed captor, a former police officer.

The growing criticism of the police response underscored what may be an early test for President Benigno S. Aquino III, who was elected in a landslide this spring. Chinese officials said they were appalled by the killings, and the chief executive of Hong Kong, Donald Tsang, complained that he had been unable to reach Mr. Aquino throughout the crisis.

In Beijing, Foreign Minister Yang Jiechi said the government demanded a “thorough investigation” and full disclosure of the results as soon as possible.

In Hong Kong, flags flew at half-staff on Tuesday, and protesters gathered outside the Philippine Consulate near the downtown financial center. Much of the fiercest criticism was focused on the length of time the police allowed the situation to continue before raiding the bus, and the extensive live news coverage, which the gunman was able to watch on a monitor inside the bus, robbing the police of any element of surprise.