Sixteen Hong Kong passengers were among 28 injured people still in hospital last night as a result of Friday's collision between two high-speed ferries off Macau. Marine authorities said they had not yet discovered the cause of the collision, which occurred in thick fog and injured 133 passengers. Shun Tak Holdings, which runs ferries between Hong Kong and Macau, said it would co-operate with any investigation. All those still in hospital were in stable or satisfactory condition. Some suffered head injuries and bone fractures. Of 12 injured Hongkongers who returned yesterday, five were admitted to Queen Mary Hospital and seven discharged. Eleven Hongkongers were among the 23 patients receiving medical care in Macau. Macau Maritime Administration director Wong Soi-man said authorities had reached no conclusions and would inspect the ferries involved and question the captains and crews. Hong Kong Director of Marine Roger Tupper also ordered an investigation into the accident. A spokesman for the Marine Department said it would liaise with Macau officials and Shun Tak. Two turbojets - the Funchal bound from Hong Kong to Macau and the Santa Maria from Macau to Hong Kong - collided at 8.30pm on Friday, each with about 220 passengers aboard. Limited ferry services to and from Macau resumed two hours after the crash but only returned to normal at 7am yesterday. Shun Tak managing director Pansy Ho Chiu-king said the company would also investigate the incident and was awaiting an official conclusion. Shun Tak representatives visited patients in hospital in Macau and the company pledged to pay for their medical treatment. Compensation would be arranged on a case-by-case basis, a company spokeswoman said. Some Hongkongers were stranded in Macau on Friday when ferry services were suspended, but were able to return yesterday.