(CNN) When the wildfires in Northern California broke out this week, they spread so fast that many residents were caught off guard.

Some told CNN that the smell of smoke or their dogs whimpering were the only warnings they got before the fires tore through their neighborhoods, forcing them to flee their homes in the middle of the night.

Now local emergency management officials and authorities are facing criticism for how they informed residents of the fires -- and how they didn't

"From what I've heard from (friends and family), no one got an alert," said Sonoma County resident Margaret Curzon, whose parents lost their home to the blaze. "Everyone was blindsided by this."

California counties and agencies used different methods to warn residents of impending danger from the fires, but some residents are saying they weren't effective. Here's a closer look at what was done and what was not.

The Wireless Emergency Alert (WEA) system

At a news conference Wednesday, state officials were questioned about why agencies had not used the federal Wireless Emergency Alert system to notify residents of the approaching fires.

You may recognize a Wireless Emergency Alert (WEA) as the screech your cellphone makes when an Amber Alert has been issued in your area.

Local agencies must apply for the authority to issue such alerts, which are sent to participating phone carriers through the Federal Emergency Management Agency's Integrated Public Alert and Warning System (IPAWS). According to the FCC , the WEA system sends alerts that are issued directly by the president, alerts that involve "imminent threats to safety or life" and Amber Alerts.

This system is credited with helping authorities catch Ahmad Khan Rahimi , who is on trial for allegedly setting off bombs in Manhattan's Chelsea neighborhood in September 2016. Three hours after the NYPD, the FBI and the Office of Emergency Management sent an alert to area residents' phones, Rahimi was in police custody.

At the time, New York's police commissioner called the system "the future."

Several state and county-level agencies in California affected by the wildfires have the ability to send the federal alerts as of August, according to FEMA . They include the Governor's Office of Emergency Services (OES) and Sonoma and Mendocino Counties.

Some statewide agencies, like the governor's OES and the California Highway Patrol, also are authorized to use the system.

But Kelly Houston, deputy director for the OES, said the state doesn't send out alerts and warnings.

"From the state level we wouldn't do that," she said. "Alerts and warnings happen on a local level. ... They decide what are the appropriate alerts for their population." Which system is used depends on the county's emergency plan, Houston said.

The California Highway Patrol's ability to use the WEA system "is limited only to Amber Alerts," said Sgt. Robert Nackey, "so the CHP wouldn't have been able to use the early-warning system to put out information regarding fires."

What alerts were used?

Mark Ghilarducci, director of the OES, told reporters Wednesday that "various counties use different ways to push information out to the public."

Those methods could include posting warnings and information on social media or using a reverse 911 call to notify landlines. Some agencies also rely on Nixle , a subscription alert service, but residents must opt in to receive its mobile or email alerts.

Sonoma County Sheriff Robert Giordano said the county -- which is authorized to send WEAs, according to FEMA -- has systems in place to notify residents with landlines, but suggested in a news conference that people sign up for SoCoAlerts, which can send notifications via cell phone, email or text messages. The county also uses Nixle, he said.

"If you don't sign your cellphone up, you don't get that service," Giordano said.

"So the message is, sign up for SoCoAlerts if you live in this county, because then it sends the message to your cell phone just like your house phone," he added. The speed at which the fires spread was also a factor in communications, he said.

Resident: 'Would've been nice to get an alert'

But those methods weren't enough to prepare Curzon or her parents, who didn't even know they existed.

Curzon's parents live in the Coffey Park neighborhood of Santa Rosa. It's the largest city in Sonoma County, where the fires have claimed 17 lives. Her mother and father lost their home in the blaze Monday.

Curzon told CNN her mother woke up around 2 a.m. to the sound of their family dog whimpering. That's when she first became aware of the fire.

Hundreds of homes in the Coffey Park neighborhood of Santa Rosa were destroyed by fire.

Neither Curzon nor her parents received any type of warning or alert ahead of the fire, she said, but she signed up for the county's Nixle alerts Monday morning after her roommate told her about them. "I didn't even know it existed before the fire happened," she said.

Curzon said she was familiar with Amber Alerts issued through the WEA system and found it "pretty disturbing" that Sonoma County had the ability to send out a warning but didn't.

"I mean, they could have sent out an alert to warn people about what was going on," she said. "Maybe they didn't because they didn't realize how quickly the fire was going to spread ... but it would've been nice to get an alert."

County: WEA would've notified too many people

Jennifer Larocque, a spokeswoman for Sonoma County, said officials chose not to send out a WEA because it would target too large a geographic area, evacuating residents who weren't in danger and causing gridlock on the roads.

"To keep everyone safe we chose not to use a mass alert that would have reached areas that are not affected by the fire, in turn keeping roads open for emergency vehicles reaching people in need," she said.

Photos: Wildfires blaze in California Aerial images showing parts of Sonoma and Napa County that have been hit by wildfires. Hide Caption 1 of 33 Photos: Wildfires blaze in California Colby Clark, left, comforts her mother, Bonnie Trexler, after law enforcement escorted them to Trexler's home in Napa, California, to retrieve medicine and personal items on Wednesday, October 11. Trexler was one of the lucky few in her neighborhood whose home was spared. Deadly wildfires have been tearing through the state, destroying homes and businesses and prompting evacuation orders. Hide Caption 2 of 33 Photos: Wildfires blaze in California Highway Patrol officers go door to door to ask Sonoma residents to evacuate their homes as a wildfire approaches on October 11. Hide Caption 3 of 33 Photos: Wildfires blaze in California Homes are destroyed in the Coffey Park neighborhood of Santa Rosa on October 11. Hide Caption 4 of 33 Photos: Wildfires blaze in California The sign of a Firestone store malfunctions in Santa Rosa on Tuesday, October 10. Hide Caption 5 of 33 Photos: Wildfires blaze in California Damaged winemaking vats and tanks stand in ashes and debris at the Paradise Ridge Winery in Santa Rosa. Hide Caption 6 of 33 Photos: Wildfires blaze in California Smoke clouds the sun from wildfires burning in Santa Rosa and Napa Valley on October 10. Hide Caption 7 of 33 Photos: Wildfires blaze in California Mary Caughey, center in blue, reacts after finding her wedding ring in the remains of her home in Kenwood on October 10. Hide Caption 8 of 33 Photos: Wildfires blaze in California Puddles of melted metal trail away from a burned-out car near Napa on October 10. Hide Caption 9 of 33 Photos: Wildfires blaze in California A TV cameraman inches closer to a burning building at a winery in Napa Valley on Monday, October 9. Hide Caption 10 of 33 Photos: Wildfires blaze in California A firefighting plane helps battle a blaze just north of Tustin on October 9. Hide Caption 11 of 33 Photos: Wildfires blaze in California A historic barn burns in Santa Rosa on October 9. Hide Caption 12 of 33 Photos: Wildfires blaze in California The Santa Rosa Hilton Hotel burns to the ground on October 9. Hide Caption 13 of 33 Photos: Wildfires blaze in California Jim Stites watches as part of his neighborhood burns in Fountaingrove on October 9. Hide Caption 14 of 33 Photos: Wildfires blaze in California Fire burns from an open gas valve near the pool area of a Santa Rosa trailer park on October 9. Hide Caption 15 of 33 Photos: Wildfires blaze in California A man rushes to save his house as a wildfire moves through Glen Ellen on October 9. Hide Caption 16 of 33 Photos: Wildfires blaze in California Kristine Pond searches what's left of her family's home in Santa Rosa on October 9. Hide Caption 17 of 33 Photos: Wildfires blaze in California Police cars block State Route 241 as smoke rises above Orange on October 9. Hide Caption 18 of 33 Photos: Wildfires blaze in California A firefighter douses flames in Santa Rosa on October 9. Hide Caption 19 of 33 Photos: Wildfires blaze in California A woman moves horses in Orange as strong Santa Ana winds blow smoke from the Canyon 2 fire toward them on October 9. Hide Caption 20 of 33 Photos: Wildfires blaze in California A firefighter douses flames at a home in Anaheim on October 9. Hide Caption 21 of 33 Photos: Wildfires blaze in California Traffic backs up as people flee Orange on October 9. Hide Caption 22 of 33 Photos: Wildfires blaze in California Santa Rosa residents sift through the remains of a burned home on October 9. Hide Caption 23 of 33 Photos: Wildfires blaze in California The remains of fire-damaged homes and cars smolder at a Santa Rosa trailer park on October 9. Hide Caption 24 of 33 Photos: Wildfires blaze in California A tent structure built for the Safeway Open golf tournament burns in Napa on October 9. Hide Caption 25 of 33 Photos: Wildfires blaze in California Fire consumes a barn in Glen Ellen on October 9. Hide Caption 26 of 33 Photos: Wildfires blaze in California Smoke rises in the hills east of Napa on October 9. Hide Caption 27 of 33 Photos: Wildfires blaze in California A man passes a burning house in Napa on October 9. Hide Caption 28 of 33 Photos: Wildfires blaze in California The remains of fire-damaged homes are seen in Glen Ellen on October 9. Hide Caption 29 of 33 Photos: Wildfires blaze in California A wildfire burns behind the Sonoma Raceway on October 9. Hide Caption 30 of 33 Photos: Wildfires blaze in California A building burns in Napa on October 9. Hide Caption 31 of 33 Photos: Wildfires blaze in California Flames overtake a building in the Napa wine region on October 9. Hide Caption 32 of 33 Photos: Wildfires blaze in California Two women hug as they watch houses burn in Santa Rosa on October 9. Hide Caption 33 of 33

Larocque emphasized the "multi-faceted approach" county officials took to notify residents, including alerts through Nixle, SoCoAlerts and the CodeRED mobile alert app, all of which require residents to sign up and opt in.

Scott Alonso, a Sonoma County spokesman, said Friday there were 10,557 residents signed up to receive SoCoAlerts, nearly 8,000 of them in Santa Rosa. That's roughly 2% of the estimated 503,070 people living in Sonoma County in 2016

The county also used reverse 911 calls to warn residents with landlines, Larocque said, and Sonoma County Sheriff's deputies went door to door to tell residents to evacuate.

But a FEMA spokesperson told CNN Saturday that agencies sending WEAs have "the option of providing geographic coordinates defining the area where the alert is to be targeted."

The IPAWS system passes the message and the preferred geographic target area to cellphone carriers, which can choose which cellular towers send out the WEA to the preferred area.

But, the spokesperson added, this requires the agency to "know the specific location of cell towers, which is not common or easily obtained information," and the targeted area could range from a small area in an urban setting to "tens of miles in rural applications."

"It's something we'll absolutely be looking into as part of our after-action plan," Sonoma County spokeswoman Hannah Euser told CNN Sunday when asked for comment.

Alerts came too late

But even some residents who were aware of the various alert systems said they fell short of what was necessary to safely warn them about the fires.

Joseph Pader, 28, lives in Soda Canyon near Napa, California. He was signed up for Nixle alerts from the Napa County Sheriff's Office but said he didn't receive a warning until 3 or 4 a.m., at which point, "it was too late to leave."

According to FEMA, Napa County doesn't have any agencies authorized to send a WEA.

It wasn't until hours later that workers from the California Department of Forestry and Fire Protection (Cal Fire) arrived and informed them they would have to leave under a mandatory evacuation notice.

Pader remained behind and helped neighbors pack and evacuate. Around 6 p.m., he watched the fire engulf his home. His family had lived there for 26 years.

"It took about 10 minutes for my whole home to burn down," he said. "It's never going to be the same. I grew up in that home. It's very close to my heart."

Napa County officials didn't respond to repeated requests for comment. The county's Emergency Services site encourages people to subscribe to local alerts through Nixle.

Pader supports his local authorities, he said, and believes they were doing the best they could. But he was disappointed with their emergency response this time.

"It could've been handled better," he said. "The resources were very thin, almost nonexistent."

One county sent a WEA

One county affected by the fires did choose to send out a WEA.

Lake County, north of Sonoma, sent an alert out to its approximately 64,000 residents around 2:20 a.m. Monday in response to the Sulphur Fire, according to Lake County Sheriff's Office spokesman Lt. Corey Paulich. Another WEA was sent out Saturday morning.

The fire situation in Lake County is admittedly less severe than in others. As of Saturday, there were only about 2,600 acres burning there.

The county used other methods as well, including Nixle and sending officers door to door. Lake County also uses the CodeRed app, Paulich said, and it has an agreement with FEMA to send WEAs through that app.

Local authorities use a mapping tool, Paulich told CNN, to select which residents in which areas should be alerted and provided with emergency information.

Officials have sent out WEAs in Lake County for weather and even to alert residents if a criminal suspect could be in their area, Paulich said.

When asked what factors authorities take into account to decide whether to send a WEA, Paulich said, "Just the fact that we had folks that were in immediate danger, and wanting to notify them of the situation."

Lake County has no reported deaths as a result of the fire, he said.