Portland police and Portland Fire & Rescue responded to a report of a gas leak in the downtown area Thursday.

Portland Fire & Rescue said the leak was reported around 7 a.m. at 813 Southwest Alder at the Woodlark Building.

The building was under construction at the time of the leak and was evacuated.

A NW Natural spokesperson said a contractor sawed through a gas line in the building, causing the leak.

Fire crews said they found the leak in the basement. Firefighters were unable to shut off the gas line and were forced to evacuate the adjacent building.

Police are assisting @pdxfire and @nwnatural with a gas leak at SW 9th & Alder. Traffic affected in area, some evacuations have been done.— Portland Police (@PortlandPolice) November 17, 2016

Shortly after, firefighters withdrew from the building and waited for NW Natural crews to arrive.

NW Natural was able to shut off the gas line around 9:20 a.m. Readings indicated there was no natural gas outside the building and crews deemed it safe to go inside. Firefighters opened windows to help ventilate the building to allow the gas to dissipate.

Crews closed Alder and Washington Streets between 8th and 9th avenues. PF&R said the traffic downtown will be affected for some time. People were advised to avoid the area.

Gas incident will affect dwtn traffic for some time. SW Washington & SW Alder closed from Broadway to 10th & all cross streets. #pdxtraffic— Portland Fire&Rescue (@PDXFire) November 17, 2016

Copyright 2016 KPTV-KPDX Broadcasting Corporation. All rights reserved.