For Hong Kong residents who suffer from accidents (e.g. traffic accident, fire etc.), emergencies (e.g. robbery, attack etc.) or casualties in the Mainland, you or your relatives should immediately report to, and seek assistance from, the local Public Security Bureau. For assistance from the police, please dial 110; for ambulance service, dial 120 (fees are generally charged for medical services, which may include ambulance fees and emergency treatment fees); for fire departments, dial 119; and for reporting of traffic accidents, dial 122.

For further assistance, please contact the Immigration Department of the Government of the Hong Kong Special Administrative Region (Immigration Department), the Office of the Government of the Hong Kong Special Administrative Region in Beijing (HKBJO), the Economic and Trade Office of the Government of the Hong Kong Special Administrative Region in Shanghai (SHETO), the Economic and Trade Office of the Government of the Hong Kong Special Administrative Region in Chengdu (CDETO) ,the Economic and Trade Office of the Government of the Hong Kong Special Administrative Region in Wuhan (WHETO) or the Economic and Trade Office of the Government of the Hong Kong Special Administrative Region in Guangdong (GDETO).

Contact numbers and addresses of the relevant offices are listed below:

It is important for Hong Kong residents to know what assistance can be provided by the Hong Kong Special Administrative Region Government when they are trapped in the mainland. For more information introduce the HKSAR Government what kind of assistance it can provide and what kind of assistance it cannot provide, as well as the handling of such cases as under arrest or serious accidents or casualties.

http://www.immd.gov.hk/eng/services/Assistance_Outside_Hong_Kong.html

While you are in the Mainland, the HKSAR Government can:

Assistance that cannot be provided by the HKSAR Government