XI'AN - One person was injured and five others remain buried after part of a subway line that is under construction caved in on early Monday in Northwest China's Shaanxi province, local authorities said.

Nine people were working underground when the accident occurred around 2:40 am on a section of the subway line No 3 in Xi'an, the provincial capital.

Four people have been pulled out, including three who were unscathed and one who is suffering from fracture. The injured has been sent to a local hospital.

Rescue of the five buried workers is under way, and safety measures have been put in place to prevent secondary disasters, sources said.