HONG KONG, Dec. 19 (Xinhua) -- Thirteen passengers injured in a fatal traffic accident on Wednesday in Hong Kong were still at the hospital by Thursday morning, with one in critical condition.

So far six people have been killed in the accident, authorities said.

By 10:45 a.m. local time Thursday, the condition of one of the injured worsened to critical at Tuen Mun Hospital, the Hospital Authority said. One was still in serious condition and the condition of the other 11 was stable. Other 26 people who were also injured in the accident have left the hospital.

At about 4:20 p.m. local time Wednesday, a bus traveling along Fanling Highway towards Sheung Shui rammed into barriers and trees, killing six people and injuring 39 others.

The 56-year-old male bus driver was arrested for dangerous driving causing death and is still being detained for further inquiries, the police said, adding that investigation is underway.