It is, in short, a humanitarian crisis, San Juan's mayor told CNN on Tuesday.
"We are finding dialysis patients that haven't been able to contact their providers, so we are having to transport them in near-death conditions," Mayor Carmen Yulín Cruz said, recalling a group's visit to two San Juan-area nursing homes this week. "We are finding people whose oxygen tanks are running out, because ... small generators now don't have any diesel."
Searchers are trying to visit every structure in the capital area, she said.
"Our bodies are so tired, but our souls are so full of strength, that we will get to everyone that we can get to," Yulín Cruz said.
Two people died in an intensive care unit in a San Juan hospital after it ran out of diesel, Yulín Cruz said. Their causes of death weren't immediately available. It wasn't clear whether those deaths were among the at least 16 deaths that Karixia Ortiz, spokeswoman for the Puerto Rico Department of Public Safety and Vilmar Trinta, spokesperson of Puerto Rico's Police superintendent, attributed to the storm.
Maria struck September 20, knocking out power for nearly all the 3.4 million residents and demolishing structures on an island already struggling after Hurricane Irma's brush earlier this month.
Nearly 1.6 million electric customers in Puerto Rico are without power, according to the Federal Emergency Management Agency and Energy Department, not counting those using generators as a backup.
Even before the hurricane hit, the island's electrical grid was functioning with "Band-Aids," Héctor Pesquera, the territory's public security secretary, told CNNE.
President Donald Trump said Tuesday
he will visit Puerto Rico on October 3, just as he inspected damage and rescue efforts in Texas and Florida after recent hurricanes in those states.
Residents in remote areas are stranded with shrinking supplies, and some haven't been able to contact their families to tell them they survived.
Coffee growers Gaspar Rodriguez and Doris Velez said the food they had left has spoiled.
"You work, work and work, and it's for nothing," Rodriguez said after losing everything.
Rescuers still are "removing people from hazardous conditions -- (people who) are ill, that can't move on their own," said Carl Levon Kustin, a FEMA task force leader from California.
"We've been working feverishly to get out to these areas," Kustin said Tuesday.
Puerto Rico Gov. Ricardo Rosselló told CNN that more support and resources for the island
While crediting the Trump administration and FEMA for responding "quickly" and "appropriately," Rosselló said, "There are some challenges and we need more resources."
'We have not lost our faith'
Near the town of Utuado, Rosario Heredia, 56, who is diabetic, is in her house, which is spewing water from every corner. She reaches high into her closet for a piece of clothing and squeezes water from it like a soaked sponge.
Heredia had hoped that help would've arrived by now -- but it hasn't.
Trees are broken and twisted on the island, leaving behind a wasteland. Roads have washed away, and others are blocked by debris.
After losing everything, some Puerto Ricans say the only thing they have left is their faith.
"Really, we are people who serve God," Wilfredo Villegas said. "And yes, we are saddened because when you lose every little thing you may have, it's not easy to recover ... but we have not lost our faith."
White House: Puerto Rico response has been 'phenomenal'
Until Monday night, Trump hadn't tweeted or made public remarks on the shattered island for several days
He began his tweets with references to Texas and Florida, where Hurricanes Harvey and Irma struck recently.
"Texas & Florida are doing great but Puerto Rico, which was already suffering from broken infrastructure & massive debt, is in deep trouble.."
"...It's old electrical grid, which was in terrible shape, was devastated. Much of the Island was destroyed, with billions of dollars...."
"...owed to Wall Street and the banks which, sadly, must be dealt with. Food, water and medical are top priorities - and doing well. #FEMA"
Asked about Trump's comments on Puerto Rico, Yulin, the San Juan mayor, said Tuesday that hurricane relief and the debt crisis are "two different issues.
"You don't put debt above people -- you put people above debt. ... Let's deal with the two issues in a separate way, because there is a humanitarian crisis," she said.
Top aides to Trump, including homeland security adviser Tom Bossert and FEMA Administrator Brock Long, went to the island Monday to assess immediate needs.
"The response today has been phenomenal," acting Homeland Security Director Elaine Duke said Tuesday.
Long said the administration's objectives continue to be to "take care of people and stabilize the situation and do everything that we can to sustain life."
Amateur radio operators help out
Because the storm knocked out radio systems used by police and utility workers, amateur radio operators are helping them communicate with each other.
Oscar Resto is the American Radio Relay League's section manager in Puerto Rico. He and about 24 fellow members of the amateur radio group in Puerto Rico have been running police and utility radio operations since Maria hit.
Trained and licensed operators have been riding with police officers and utility workers with battery- or generator-powered kits.
And the American Radio Relay League is just getting started.
On the US mainland, CEO Tom Gallagher's phone lit up around 10 p.m. Friday. It was the Red Cross.
"We need 50 of your best radio operators to go down to Puerto Rico," Gallagher says a Red Cross representative told him.
Less than 48 hours later, 50 of them had signed up for a three-week deployment to Puerto Rico.
"Everything from rich guys to firefighters," Gallagher says.
Gallagher's team went to work with their manufacturers and dealer partners, scrambling to compile the self-sustaining kits the operators will need in Puerto Rico.
Long lines at San Juan airport
Hundreds of people have packed the main terminal at San Juan's Luis Muñoz Marín International Airport this week, hoping to escape the devastation -- but leaving hasn't been easy.
Because of damage to radar and other equipment at the airport, only about 10 commercial flights between San Juan and the US mainland could take off and land Monday -- and the same number is scheduled for Tuesday, airport authorities told CNNMoney
People are waiting in a main terminal that -- because it is running on limited emergency power -- has no air conditioning.
"Everyone is in the same boat, trying to get out," Leyla Colon, standing in line at the airport Monday, told Reuters. She said she couldn't buy tickets before she arrived at the airport, because she didn't have Internet or cellphone service.
"At this point I'll buy a ticket on any flight to get out of here," Colon told Reuters.
Dozens more flights with relief material -- meals, water and generators -- have come into the airport, the Federal Aviation Administration said.
The first commercial flight from San Juan to New York's John F. Kennedy International Airport since Maria landed Monday night, to the relief of the 200 passengers' relatives.
Sarita Mongelli's parents, in their 80s, were on the flight.
"I can't describe the feeling after five days (of) not talking to them," Mongelli told CNN affiliate WABC
. "I can't tell you what they've gone through -- horrible, horrible conditions -- and at this age, it's very hard for them."
Mongelli said her parents want to return to Puerto Rico but won't be going back anytime soon.
"Whatever's left of their life right now, they need to be safe with their children, not alone," she told the TV station. "We can't ask for more, I got them home -- I'm taking them home with me now."
'We're on a mission'
At Atlanta's international airport, aid workers were preparing Tuesday to board a charter flight to San Juan. Among them were 31 members of the New York City Fire Department, many of whom are of Puerto Rican descent.
"As Puerto Rican New York City firefighters with family that live in Puerto Rico, devastated by Hurricane Maria, we're on a mission to do what we can as best as we can, to get to all the people we can," said Lt. Joe Montalvo, a fireman from Battalion 57 in Brooklyn.
The firefighters loaded supplies onto the plane, including special cases of blood in refrigerated containers.
Montalvo said he had yet to speak with relatives living on the island.
"Phone service is still down, cellphone service is limited," Montalvo said. "My family (lives) in the southwest corner of the island, and we haven't heard anything from anybody."
He added, "We're hopeful they're OK."
CLARIFICATION: This story has been updated throughout to reflect the full last name of San Juan Mayor Carmen Yulín Cruz.