As many as 20 homes along a street in Burnaby were evacuated as the RCMP investigated a suspected drug lab in the Vancouver suburb.

The lab was discovered on Thursday in a home, where one man was arrested, after residents of the 7900 block of Nelson Street saw steam rising from a manhole and called police.

The RCMP and fire crews quickly cordoned off the street.

Cpl. Jane Baptista saidthe residentswere asked to leave for their own safety.

"Quite often with any of these drug labs with the unknown chemicals involved, some of them can in fact be explosive, some are not. And until we know what we're dealing with when we locate something like this, we will evacuate until we ascertain the neighbourhood is safe."

Four firefighters, two city workers and an environmental expert were treated at the scene for exposure to the fumes.

The Mounties searchedthe home suspected of being a drug lab and arrested one man.

There's no word on what kind of drugs were being produced in the home where the man was arrested.