MACAO?- A tour bus rear-ended another in a chain road accident on Tuesday in Macao, with 57 people injured, the special administrative region's police authorities said.

Macao's Public Security Police Force told Xinhua that the accident happened around 16:00 local time (08:00 GMT), when two tour buses in the same lane wanted to avoid a sedan in front of them. Both had sudden braking and the second one hit the rear of the first.

According to police investigation, both drivers and the driver of the sedan have passed the alcohol test. The police said the accident site is not a location where car accidents often happen.

Macao's Health Bureau said 24 men and 33 women were injured and then sent to hospital for treatment. Most of them sustained contusion and bone fracture, and two of them were wounded badly. All of them have no life-threatening injuries.

The Health Bureau added that the 57 people were aged between 19 and 79. Two of them are Macao citizens, and others are members of two tour groups from the Chinese mainland.