A Chinese cobra (inset) was found inside a Chai Wan residential building. Photos: Google Maps, AFCD

A security guard spotted a five-foot-long Chinese cobra in a residential building in Chai Wan on Hong Kong Island on Wednesday morning.

At about 10am, the security guard found a black cobra in a room on the ground floor of Goldmine Building in Chai Wan when he was patrolling.

He called police immediately and a snake expert was brought in to handle the problem. The snake specialist managed to subdue it within five minutes, Apple Daily reported.

The male snake, about five-foot long and 10 years old, was a venomous naja atra species, more commonly known as a Chinese or Taiwanese cobra. It’s considered a variant of a spitting cobra whose venom can harm a person’s central nervous system if it contacts the eyes.

The snake expert suspected that the animal was washed down the hill into the drainage system in Chai Wan, Sing Tao Daily reported.