A fully functioning methamphetamine lab was discovered by a contractor working in an apartment suite in Winnipeg.

While police were on scene investigating and dismantling it, the tenant returned and was arrested. And when officers went inside the suite, it was "in the process of a cook," said spokesman Const. Rob Carver.

"When we went into this lab, the stove was on, elements had to be turned off," he said.

Members of the police service's clandestine lab team were called to the building on Mayfair Avenue, between Harkness Avenue and Main Street, around 8:30 p.m. on March 30.

The building was evacuated and two transit buses were brought in to shelter residents while the lab was taken down.

The suite was cleared out by members of the Winnipeg Fire and Paramedic Service, a hazmat unit and the clandestine lab team.

"The toxic chemicals that are used in these labs can produce gases that would kill someone walking into the room very quickly," Carver said.

"They're incredibly dangerous. As well, there is explosive concerns."

Items seized from the suite included lab equipment, a pressure cooker, a chemical suit with gloves, a self-contained breathing apparatus and the following chemicals:

Drano.

Acid.

Red phosphorous.

Samples have been sent to Health Canada for analysis.

A 29-year-old man has been charged with producing a scheduled substance, possession for the purpose of trafficking methamphetamine and two counts of mischief.

The mischief charges come from the man's actions after he was arrested, said Carver.

"The accused became unbelievably aggressive while in custody and was able to damage one of our holding cells," he said.

The last time the police came across a meth lab was in December 2017 "and it was far less sophisticated," Carver said.

The discovery of the lab disturbed Mitchell Campbell, who lives in the building.

Mitchell Campbell says he was woken in the middle of the night by police who told him the building was being evacuated. (Tyson Koschik/CBC )

He said he was woken by police in the middle of the night, telling him the building was being evacuated.

He was asked to wait outside in a bus they had reserved for tenants.

"This is a community of families. It's really hard to think something like that would happen so close to home," he said.