PORTLAND, Ore. -- A contractor sawed through a gas line inside a Downtown Portland building Thursday morning, causing a gas leak that evacuated buildings and shut down streets for several hours, according to NW Natural.

Fire crews and police were called at about 7 a.m. to the gas leak inside a building at 813 SW Alder Street.

About three hours later, at 9:56 a.m., Portland Fire & Rescue tweeted that people were being allowed back into buildings and streets would be opening shortly

After firefighters arrived and conducted an initial investigation, they were pulled out of the building and the building next door was evacuated. Northwest Natural crews were on scene working to shut the gas off, and they asked that emergency crews stay at least 100 feet away from the building.

Just after 9 a.m. fire officials reported that the gas source into the building had been shut off, but crews remained cautious as they weren't sure all the gas had cleared out.

"We are working very cautiously and carefully because of our experience her in Portland on Northwest 23rd," said Portland Fire & Rescue Lt. Rich Tyler. "We do not want anyone, including our own firefighters, to be hurt. So we are taking every precaution we can, while at the same time wanting to mitigate the emergency and be able to have all of us go on with our day."

This gas leak came nearly a month after a natural gas leak caused an explosion on Portland's Northwest 23rd Avenue on the morning of Wednesday, Oct. 19. That blast injured eight people, badly damaged a building, and forced businesses to close for weeks.