Updated with developments from 4 p.m. news conference

A massive explosion, apparently ignited by a natural gas leak, ripped through a building Wednesday along the popular Northwest 23rd Avenue shopping district, causing destruction and injuring eight people, including three firefighters, authorities said.

NW Natural employees along with Portland firefighters responded to a natural gas leak reported at 8:55 a.m. in or near the 500 block of Northwest 23rd Ave., said spokeswoman Melissa Moore.

"When we got there (at 9:10 a.m.), we evacuated the building," Moore said. "There was an ignition. We don't know the source."

The explosion happened at 9:38 am., the utility reported. Some witnesses said there were two blasts.

One building that contained a bagel shop, a tattoo parlor and eyewear business was destroyed, while a spa and condo building next-door sustained heavy damage.

Firefighters were inside one of the buildings when the explosion occurred, said Portland Fire & Rescue spokesman Lt. Rich Chatman said. More than 100 firefighters responded.

The bagel building was listed on the Historical Registry of Buildings; the other was designed by well-known Portland architect Brad Cloepfil and is owned by Robert and Ann Sacks, whose eponymous company is well known for its tiles.

No one received life-threatening injuries; two of the firefighters sustained broken legs and the other underwent surgery for an undisclosed injury. Two police officers and three civilians were also hurt. Authorities didn't say what their injuries were.

Portland Bagelworks was the anchor of the building that was destroyed, though it was unconfirmed whether the explosion occurred in the restaurant. The Dosha building next door also sustained major damage.

Portland firefighters responded rapidly after the explosion. An ominous, billowing, black cloud hovered over the Northwest 23rd area, known for its bustling scene of trendy shops and restaurants.

Moore said there was construction underway at or near the address. She did not know the identity of the people involved in construction.

"A third party was digging," Moore said, adding, "That's why we want people to call before they dig."

Brittany Hughes, manager of the Portland Bagelworks, said a construction worker came into the shop and said crews had hit a gas line. He left before Hughes could say anything.

"The next thing I know my baker is telling me he smells gas," she said.

She called shop owner Richard Bartel, who contacted NW Natural. Firefighters arrived quickly and evacuated the area.

"And about 20 minutes or so after they evacuated our shop, it exploded," he said.

In a late afternoon news conference at the site of the explosion, Portland Fire Chief Mike Myers said, "I have not seen devastation like this in my entire career." He said the work of firefighters prevented people from dying.

The firefighter in surgery was Lt. Peter St. John, he said. St. Johns made the decisions to pull fire alarms, evacuate buildings and have firefighters put on air masks, he said.

"This man saved a lot of lives today singlehandedly," Myers said.

Not long after Sara Johnson arrived at Dosha about 8 a.m., the construction worker rushed over and told them about the gas leak across the street.

The worker said to alert him if they smelled anything. It wasn't long before Johnson, assistant manager of the salon, sensed something amiss.

"A few moments later we started to smell some gas," Johnson said. "It didn't smell right."

She alerted the construction workers, who were also working on her side of the street, she said. It wasn't clear what they were doing.

Northwest Natural employees showed up about 10 minutes later and monitored the air, Johnson said. They didn't find a trace.

But then firefighters showed up and told everyone to evacuate. The six people at Dosha - all employees, including one who was there for an appointment -- walked onto Glisan toward Northwest 22nd Avenue.

"They kept pushing us farther back," Johnson said. "Maybe 15 minutes after we evacuated, it exploded. It exploded twice, and you saw glass shattering and smoke. The smoke was getting thicker and thicker. It was scary. "

She said no residents or pets were home in the apartments above the salon.

But the explosion destroyed the building, said Kimberly Johnson, chief operating officer for Aveda Institute. The institute and salon have the same owners.

"It looks like it blew from within our building," Kimberly Johnson said. "There is glass everywhere, and the building is pretty much gone."

Legacy Emanuel Medical Center was treating and evaluating two firefighters, a police officer and a civilian, spokeswoman Vicki Guinn said at about 11:15 a.m.

By early afternoon, all but one firefighter had been released.

Four ancillary buildings of Legacy Good Samaritan Medical Center were without power after the explosion, Legacy spokesperson Megan Deisler said. She said power briefly flickered at the main hospital but continued. Deisler said most patients were being sent to Legacy Emanuel Medical Center but Good Samaritan also was prepared to accept patients.

Rubble was strewn on the sidewalks and into the intersection of Northwest 23rd Avenue and Glisan Street. At noon, smoke continued to pour out of the charred rubble, as firefighters continue to spray it down.

Safety and reliability program staff from the Oregon Public Utility Commission were sent to the scene to begin evaluating the utility and fire department response and procedures for keeping people safe at the scene.

The commission filed a report with the U.S. Department of Transportation's Pipeline and Hazardous Materials Safety Administration, and inspectors from that agency are likely to be involved in the investigation of the explosion, which would be led by the Portland Fire Marshal's Office.



The commission "is going to look at NW Natural's policies and procedures to see if they were in any way negligent" in terms of what could have prevented this, said Lori Koho, who administers Oregon's pipeline safety and reliability program.



She said NW Natural has an active public awareness and damage prevention program, including its Call Before You Dig campaign. But there is so much construction underway, with so many contractors looking to get things done quickly, that third party line breaches are not infrequent, she said.



"There are line hits way too often, but they usually don't explode," Koho said.

A NW Natural official said that gas to about 115 customers has been shut off. PGE has also shut off power for about 2,000 in the area.

Residents and others nearby described feeling the percussion and their power going out.

Dylan Short, a 28-year-old worker at Pizzicato across from the site of the explosion, said he was going about his business when firefighters arrived and told him there was a gas leak.



Asked if he and his coworkers should leave, Short said firefighters told them to "stay put" while crews established a perimeter.



Within minutes, however, Short said he was hit with multiple shockwaves as the business across the street exploded.



Thankfully, Short said, he and his coworker were protected by a wall.



"If we had been in any other part of the restaurant we would have been injured by shrapnel for sure," Short said.



Immediately after the blast, Short said he saw flames spewing from what was left of what used to be a multistory building.



"It was three stories before, and now it's just a pile of rubble," he said.



In the aftermath of the explosion, Short was shaken but unhurt. He said he saw one woman being helped from the scene and a firefighter with blood streaming down his face.



Still, Short felt fortunate.



"It was lucky for us we were behind that wall," he said. "But its unfortunate for the store and the firefighters. Hopefully not too many people were injured."

Nick McAnally, staying in an Airbnb near the explosion site, said he and his girlfriend felt two explosions, separated by 10 to 20 seconds.

"All of a sudden we felt this huge explosion. It shook the whole house" in the 2200 block of Northwest Glisan, McAnally said. "We froze and looked at each other, and that's when the second explosion happened. It still shook the house, but it was maybe half the intensity of the first explosion."

Before the blasts, McAnally said he and his girlfriend, vacationing from Wichita, Kansas, noticed something was amiss when a fire truck arrived about 9 a.m. in front of the Airbnb. A firefighter emerged from the truck and immediately began attaching a hose to a nearby hydrant.

"We thought that was odd," he said.

The first blast happened moments later, he said.

McAnally saw people running from the area. He also took photos of the scene, including an image of a bloodied firefighter.

"I don't know why they would be inside the building if there's a gas leak," McAnally said.

After the blast, a NW Natural employee walked through the neighborhood. McAnally asked what he and his girlfriend should do.

The employee replied, "If I was you I'd get out of here."

McAnally headed to a Starbucks closer to the Pearl District and plotted the next part of their day: a Segway tour of downtown.

Kumar Naharaja, 50, said he was settling into breakfast about 9:40 a.m. when he felt a jolt, "like an earthquake."



"It shook my apartment," he said.



Naharaja lives on the fourth floor of an apartment building near Northwest Lovejoy and Northwest 25th Avenue. He peered out his window and saw smoke that he mistook for morning fog.



"I heard a loud explosion and someone cried, 'Wow!'" he said.

"It sounded and felt like a bomb," said an employee of Westover Dental Clinic, 419 N.W. 23rd Ave., who did not want to be named. "It was that loud. It shook the whole building."

Cameron Oxenham lives in an apartment building across Northwest 23rd Avenue from the explosion site.

"It looked like a bomb had gone off," Oxenham said before leaving the area.

Eric Ohman was home in his 24th floor apartment in the 735 St. Clair Building, which is at West Burnside Street about four blocks from explosion. He said it shook his building and sounded like a "Dumpster being dropped off a roof, like a kind of hollow 'whoompf.'"

Firetrucks, ambulances and police cars converged on the popular business district as a plume of acrid smoke billowed from the damage, darkening an unusually sunlit Portland autumn sky.

Portland Commissioner Dan Saltzman, who oversees Portland Fire & Rescue, left Wednesday's City Council meeting at about 10:15 a.m. and was on the explosion scene shortly afterward.

Firefighters had been inside the bagel shop building -- either investigating the leak or ensuring the building had been fully evacuated -- at the time of the explosion, Saltzman said.



"That northeast corner is totally gone, and possibly something to the north. It's pretty surprising, given what looks like a large-magnitude explosion, not having more injuries," he said.

Students and faculty at Metropolitan Learning Center, a citywide magnet school for students in kindergarten through grade 12, were evacuated from the building two blocks from the explosion site on Northwest Glisan Street. They were bused to Portland Public Schools headquarters, near the Rose Quarter. School officials provided lunches for the 425 students and notified parents they could pick them up early.

An initial report the students would be sent to Lincoln High School was incorrect.

TriMet also is providing buses to support first responders in evacuating a school near the explosion scene in Northwest Portland, spokesperson Roberta Altstadt, said. TriMet's Line 15-Belmont/NW 23rd buses are detoured around the closed streets, and lines 15 and 77 have been delayed.

Fruit & Flower Childcare Center is located less than two blocks from the scene, near Northwest 24th Avenue and Hoyt Street, and children were seen being evacuated from the center, some in cribs.

The Multnomah County Health Department advised Wednesday morning that people take precautions to not breathe the explosion's heavy smoke, noting that high concentrations of smoke can cause trouble breathing, irritation of eyes, throat and lungs, and skin irritation.

Lena Cottrell was at the nearby Fresh Skin Studio when she heard a loud boom, shaking the entire building and knocking wall hangings to the floor. At first, Cottrell thought a car had hit the building.

One of the studio's employees, Haley Atterbury, ran outside. She saw flames and smoke coming from the Bagelworks building.

"I was panicked," she said. "It was a chaotic moment of not knowing what to do.

Shaddie Yazd, a hair stylist at Dosha, said, "It's all kind of a blur right now."

And Quintae McKinney, operations manager at Dosha, added, "It happened within 30 minutes of our business being open," McKinney said. "We had some managers and some retail staff there. Our full staff hadn't shown up yet.

This is not the first time the building's been struck.

"Unfortunately, we had a dry run of this last year," Kimberly Johnson said. A water leak about the same time last year destroyed the inside of the building.

"It happened overnight," Kimberly Johnson said. "There was 2 inches on every floor."

It took three months to restore the salon. And now the company is again scrambling, trying to figure out how to accommodate clients and staff.

"It was beautiful," Johnson said.

Dosha is trying to figure out what to do about people who had booked appointments and the employees who depend on the salon for their livelihood.

"We're pulling together to get it figured out," Sara Johnson said. "I'm just happy everyone's safe."

At the news conference, a Fire Bureau spokesman said any residents displaced by the explosion can get assistance through the Red Cross, which has set up an assistance center.

The bureau also plans to release on Twitter the names of buildings that are safe for residents to return to. The number displaced has not been determined, but 181 people live on the affected block.

Explosion at scene of natural gas leak at NE 23rd & Glisan. Multiple firefighter injuries. Avoid area. pic.twitter.com/X8lNS7bNWE — Portland Fire&Rescue (@PDXFire) October 19, 2016

3rd Alarm Gas Incident taking place at NW 23rd and Glisan. Avoid area. PIO enroute, media staging info tba. @PBOTinfo — Portland Fire&Rescue (@PDXFire) October 19, 2016

Huge explosion at 23rd and Glisan in Portland. My son took this. pic.twitter.com/XbOYkjEnY4 — Jack Ohman (@JACKOHMAN) October 19, 2016

Alert: Avoid NW 23rd & Glisan this morning as @PDXFire incident. Expect road, lane closures & traffic delays. #pdxtraffic #pdxbikes https://t.co/5hRfJOtqgT — Portland Bureau of Transportation (@PBOTinfo) October 19, 2016

LIVE on #Periscope: explosion in nw Portland. My mom who lives nearby said it felt like a semi truck hit her buildi… https://t.co/w5jBaLqgUP — Mike Bivins (@itsmikebivins) October 19, 2016

-- The Oregonian