A former armed police officer, a 13-year-old boy and a young nurse are among the people who participated in immediate rescue efforts when a bus plunged into a sinkhole caused by a road collapse in Xining, Qinghai province, on Monday.

Footage shot by security cameras showed several people on the scene rushed to the edge of the hole and leaned forward, apparently in an attempt to rescue passengers as the bus gradually tipped into the sinkhole.

A passerby seen crouching on the edge of the chasm and suddenly falling inside as the road collapsed again was later identified as Sun Wanhong, a former officer with the armed police force in Qinghai province.

Sun, who suffered several bone fractures to his lumbar during the rescue, is receiving treatment at a hospital. He told China Central Television that cable explosions, water pipeline ruptures and tumbling dirt had complicated the danger inside the hole.

"Many people stranded in the hole were crying and shouting for help as water and dirt kept pouring in, so I told them to stay calm and reassured them that rescuers will come and save us," he was quoted as saying.

"I also strived to haul up a man who was halfway buried in mud."

Sun reportedly rescued three people.

Also captured by surveillance footage were the valiant actions of a 13-year-old boy, who was riding the bus with his family members when the incident occurred.

The boy was seen rescuing an infant from the edge of the hole and then heading back to save others. The second collapse also caused him to fall in, a scene that gripped the hearts of many.

The boy is now undergoing treatment at a hospital and is in stable condition, the Beijing News reported. However, his mother was reportedly killed during the incident.

Jiao Baoyun, a nurse with the Qinghai Red Cross Hospital, had just gotten off the bus when it began toppling into the chasm.

"I work at the hospital's emergency department, so my gut reaction at that moment was to return and save people," he said during an interview with Xinhua News Agency.

After another stretch of the road caved in, Jiao found himself trapped inside the sinkhole.

"I immediately called fellow nurses at my workplace to send ambulances because the hospital that I worked with is the nearest," he was quoted as saying. "In the meantime, I kept telling everyone to stay calm and wait for the rescue force."

Jiao is also in stable condition and is now recovering at the hospital.