A “catastrophic failure” of a water main caused millions of gallons of water to flood streets, homes and businesses in Northeast Portland on Saturday, Portland Water Bureau officials said.

A 30-inch-diameter pipe gave way around noon near the intersection of Northeast 23rd Avenue and Skidmore Street, the authorities said. A geyser was seen bursting several feet into the air from the site of the break.

The gusher, which continued for hours, turned Northeast 24th Avenue into a north-flowing river from Skidmore Street to Northeast Alberta Street, inundating homes along both sides, and sent water flowing into businesses, homes and basements on both sides of Alberta Street from Northeast 25th Avenue to Northeast 31st Avenue.

“This is an all-hands-on deck issue,” said Mayor Ted Wheeler, who implored bystanders to stay away from the water to avoid hazards like contamination from the sewer system or unstable ground.

It’s unclear what caused the rupture, but Water Bureau spokeswoman Jaymee Cuti said it was likely a combination of old age and pressure due to freezing and thawing of the ground this winter.

Dozens of intersections are affected, and Pacific Power said more than 11,700 area residents were initially without electricity and gas, as officials intentionally cut power to homes inundated with water and to help make it safe for Water Bureau workers to dig into streets.

Police told residents to treat all non-functioning traffic lights as four-way stops. Scott Bolton, a spokesman for Pacific Power, said it would take three to four hours after the water shutoff to restore all power. “We’ve got to make sure we have safe conditions before we start re-energizing circuits," he said. The utility is asking residents with flooded basements to call in so workers don’t re-energize an unsafe area.

By 7 p.m., Pacific Power reported that it had restored electricity to nearly all of the more than 10,000 area residences and businesses impacted. About 10 customers, though, were still without power because they had equipment damaged by water.

Cuti said Water Bureau workers were able to greatly diminish the flow of water coming from the break within an hour or two by using valves on the big pipe to stop the flow to that point in the line. Some of those valves hadn’t been shut in decades and were difficult to shut, a Water Bureau official said.

Storm drains were put into overdrive clearing away millions and millions of gallons of water unleashed by the break. By 5 p.m., all the water had drained from Alberta Street and much of Northeast 24th and 25th avenues as well. But the water continued flowing at reduced levels from the broken main and blocks of Skidmore Street and Northeast 24th were still inundated.

The situation currently at the site of the break. The road surface has clearly caved in. pic.twitter.com/4HHiy714pB — Elliot Njus 🏠🏢🏗 (@enjus) March 16, 2019

As of 4 p.m., about 10,000 Pacific Power customers were without power, utility officials said. The utility turned off power to homes and businesses from Northeast 18th Avenue east to Northeast 47th Avenue between Northeast Thompson Street and Columbia Boulevard.

Now a few blocks away from the flood zone and the power came back on. I heard cheers from a gathering in a home nearby. pic.twitter.com/xKyOSfyoFY — Elliot Njus 🏠🏢🏗 (@enjus) March 17, 2019

Power was restored after the flooding was controlled, they said. Power restoration was described as very labor intensive, requiring more time than a normal power outage, they added.

Restaurants on Alberta Street, stripped of access to electricity, risk losing thousands of dollars of perishable food, said Fayren Chang, co-owner of Just Bob, a cafe. The cafe lost thousands of dollars of business Saturday when it was forced to close.

“It came down the street and it was like a wall of water," she said. "We’re lucky we’re built a little higher.”

Water flooded across Alberta and jumped up onto the sidewalk, but not high enough to get into Just Bob, which has its entrance a step up from the sidewalk.

“It’s pretty devastating for about any business here," Chang said. "It’s the weekend, it’s St. Patty’s Day tomorrow.”

Flow of water has dramatically reduced again, even from a half hour ago pic.twitter.com/hgDDLGjAZy — Elliot Njus 🏠🏢🏗 (@enjus) March 17, 2019

Portland’s water system experiences about 200 water line breaks per year, Cuti said. But most of them are in 4-, 6- or 8-inch service lines. The line affected Saturday was a major transmission pipe carrying water from Kelly Butte east of I-205 in Southeast Portland to inner Northeast Portland, Cuti said.

Officials are advising residents in the vicinity that the tap water in the area might be discolored. Tap water may appear cloudy or brown from sediment that has entered the water, officials said, and while the discoloration may affect color, odor and taste, there are no health hazards associated with it. The affected area includes Northeast 21st Avenue to 30th and Alameda to Northeast Rosa Parks Way.

The standing water’s another matter. The city says the standing water is associated with various health hazards and warned the public not to touch it.

The flooding is ongoing, although with greatly diminished flows, and firefighters and workers with the Portland Water Bureau are trying to bring it under control. By 4:30 p.m., water flow had been reduced by about a third, but officials still weren’t sure when the flooding into the street would end. As the water recedes, the city warned, sewage may back up into local homes and businesses. If that happens, the city told residents to call the Portland Bureau of Transportation Maintenance Operations Dispatch at 503-823-1700.

PBOT officials believe some roads were undermined by the flooding and will have to be rebuilt. They could be closed for days.

This storm drain at NE 24th and Going is doing yeoman's work pic.twitter.com/3UyrOF5NYN — Elliot Njus 🏠🏢🏗 (@enjus) March 16, 2019

To completely fix the problem, Cuti said, Water Bureau workers will need to locate the break, dig out the old pipe, replace it with a new section of 30-inch pipe, then attach the new section of pipe to the existing line. Despite having put every emergency crew into action, that will likely take a couple days, she said.

The break left a jarring scene as water streamed unabated onto streets in Portland’s Sabin neighborhood and flowed over Northeast Alberta Street and north toward Concordia University, about a mile away. Water was seen bursting through seams in the road in some places. The Portland Bureau of Transportation set up a sandbag site at Northeast 26th Avenue and Northeast Mason Street for anyone needing to protect their property. “Bring your own shovel!” PBOT tweeted.

Many took to social media to post photos and videos of the flooding.

Water is still gushing from the broken pipe. The water is a little past my ankles while standing on the sidewalk. pic.twitter.com/imfhdFG4Q3 — Everton Bailey Jr. (@EvertonBailey) March 16, 2019

Firefighters were seen carrying bystanders piggyback-style through ankle-deep water so they could reach their vehicles or cross flooded areas.

Officials are asking people avoid the area and stay clear of the water.

“Being in or near this water is extremely hazardous,” the Fire Bureau tweeted. “Weakened surfaces, open manhole covers and unclean water to a mention a few. Please stay out of the area!”

A Portland firefighter is carrying people on his back to their cars. They had to come back with this woman because she forgot her keys. pic.twitter.com/Udfga1qVTm — Everton Bailey Jr. (@EvertonBailey) March 16, 2019

Still, bystanders gathered on sidewalks to watch the sudden waterworks. One person brought a kayak and stood on it as it floated down the streetside stream.

Here’s the situation out here right now. pic.twitter.com/62t3DVPcEi — Everton Bailey Jr. (@EvertonBailey) March 16, 2019

Customers affected by the power outage should receive more information via direct phone calls, Pacific Power officials said. Pacific Power’s outage map and its Twitter account will post frequent updates.

“We want to thank customers for their patience in this unusual situation as we work with the city,” said David Lucas, vice president of operations. “Safety has to come first. Flooding basements, many of which contain circuit breakers, (are) a major risk. We urge everyone to be cautious.”

Homeowners experiencing sewer back-ups were advised to contact the Portland Bureau of Transportation at 503-823-1700. The roads agency, not the sewer bureau, will be clearing sewer lines, officials said.

Some residents may be evacuated and officials have contacted the area Red Cross for help. Twelve households that had to be evacuated were allowed back inside at about 4 p.m. but will be without electricity and gas.

The total damage is unclear.

This is a breaking news story and will be updated with new information.

-- Gordon R. Friedman; gfriedman@oregonian.com

-- Elliot Njus; enjus@oregonian.com

-- Everton Bailey Jr.; ebailey@oregonian.com

Reporter Betsy Hammond contributed to this story.