Officials and fire crews in the city of Herne, in western Germany, were combing every vent and corridor of an apartment block Thursday in search of a deadly cobra.

"We are trying everything to reinstate security so that people can return to their apartments," Herne Mayor Frank Dudda said during a press conference.

The roughly 4.6-foot-long cobra escaped from one of the residents' apartments as early as Sunday, having been spotted in a hallway. Four buildings within the block, connected by a cellar, were evacuated with its more than 30 residents being forced to stay with family, friends and at a city shelter.

While officials believe the cobra is likely in the cellar, people living in the area have been warned to avoid walking through high grass.

Snakeskin found in the cellar of the building earlier in the week wasn't enough evidence to ensure the reptile was still in the building, the city's council head Johannes Chudziak said.

A deadly monocled cobra at the doorway of a residential building in Herne, western Germany, from where it escaped. Collin Bleck / AFP - Getty Images

The antivenom required to treat this particular snakebite is in store at a nearby Duesseldorf hospital in the event someone is bitten, officials said.

A special unit of the local fire department and snake experts have been employed to conduct the search. A special double-sided sticky tape was laid out in areas of the building in attempt to trap the venomous reptile. There are also considerations to seal the building with foil and then release a biological gas that would kill the reptile.

The man who owned the cobra kept another 20 snakes in his apartment, all of which have been confiscated by authorities. How and why he owned the animals is unclear.

The incident has reignited public debate over the introduction of a dangerous animal law that would prohibit residents from keeping such species. "The present regulations are not sufficient," Dudda said Thursday.

State lawmakers had in tried to enforce a law to ban people from keeping animals such as venomous snakes, crocodiles, scorpions or big cats in 2014, according to the German public broadcaster Deutsche Welle. But the legislation faced pushback and was eventually dropped.