Police Chief George Scherb said no injuries were reported.
Traffic around the scene was still being rerouted at 7 p.m., when many roads on the west side of town were still gridlocked.
West Crescent Avenue, between Hillside Avenue and West Allendale Avenue, will continue to be closed into the Friday morning rush hour, officials said.
Drivers are urged to find alternate routes.
Firetrucks from Allendale, Ho-Ho-Kus and Wyckoff responded.
“There’s a lot of equipment out there,” Firefighter Rick Cauwenberghs said.
He saw gas fumes “forcefully” coming out of the ground and shooting up some 15 feet in the air when he drove by around 3 p.m.
“Public service is trying to shut down the leak now,” Cauwenberghs said at 5:10 p.m. Thursday.
“But they have to do it slowly because it’s such a big main. They’ve got to gradually shut it down so no back pressure builds up and explodes somewhere else.”
At 5:30 p.m. firefighters were knocking on doors in surrounding neighborhoods, including Mallinson Street and Park Avenue.
At 6:40 p.m., the Allendale Office of Emergency Management sent out messages to residents asking that they avoid all non-essential travel.
“As part of the repair process,” the message said, “there will be a controlled release of natural gas.”
Residents were alerted to call police if they smell natural gas inside their homes and to call 911 in the event of an emergency.
The 7:30 p.m. Allendale Mayor and Council meeting was canceled because, according to the borough’s Facebook page, “access to Borough Hall is severely limited.”
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