The intensive care unit was sweltering in the afternoon heat, the doctors covered in sweat and fanning themselves with their scrubs. Already compromised by weakened physical conditions and a lack of food and water, intubated patients melted under individual fans.

“It’s an oven,” said Cesar Castillo, a surgery resident at Centro Médico Hospital in San Juan. “It’s hard to get their fevers down.”

It has been more than a week since Hurricane Maria devastated Puerto Rico, and the humanitarian crisis that has ensued is nowhere more obvious than in the health-care facilities that often are without electricity and always are overwhelmed.

About half of the island’s hospitals — 33 — are functioning. Those that are accepting patients have intermittent power and have to pray that the diesel fuel running their generators will last until the next truck arrives.

Forced to take people from hospitals that have closed, hospitals outside San Juan are over capacity and overwhelmed by patients. Some hospitals have become more akin to community centers, with people lining up to use the cafeterias, and relatives of patients trying to use the showers and bathrooms because they don’t have water at home.

Doctors across Puerto Rico say that many patients, particularly elderly ones, are arriving at hospitals in deteriorating condition because they waited too long to seek treatment, in many cases because they couldn’t find the gas to drive. Others worry that since so many people are without water and electricity, infections and diseases will spread more easily.

Numerous patients already have been treated for dengue — a mosquito-borne virus — in Hospital del Maestro, a small facility in the Hato Rey neighborhood of San Juan. Many people have arrived with herpes, asthma and respiratory problems.

“I lost count of how many people have come with conjunctivitis,” said Lisa Matos, supervisor of the hospital’s emergency room. Conjunctivitis, or pinkeye, is often caused by lack of hygiene, Matos said. Without running water in their homes, people are washing their hands less.

The lack of power, water and fuel is affecting hospitals as it is affecting much of society here.

The San Jorge Children’s Hospital in Santurce was without power for nearly eight hours earlier this week after running out of diesel for its generators; half of the 90 patients there were either transferred or released.

Domingo Cruz, a San Jorge administrator, said his hospital desperately needs a steady supply of fuel. Some staff members are staying at the hospital so as not to waste gas commuting.

“Nothing can function without power,” Cruz said. “Outside right now, we have a tank that holds 4,000 gallons of diesel. The hospital’s two combined building use 1,500 gallons every day.”

Cruz said the situation is going to get worse before it improves.

“During November and December, it’s going to get bad,” Cruz said. “There are going to be cases of dehydration, there are going to be cases of dengue fever. There are going to be people with diabetes who haven’t been taking care of themselves because their focus has been on rebuilding their lives and taking care of their families.”

Patients wait outside the Centro Médico Emergency Room in San Juan, the largest public hospital in Puerto Rico. (Dennis M. Rivera Pichardo/For The Washington Post)

Centro Médico gained electricity for about two days, but lost it again, forcing the hospital to rely solely on generators. Just four of the hospital’s more than 20 operating rooms have been open on a daily basis, because the others lack water or fuel, said Segundo Rodríguez Quilichini, chancellor of the University of Puerto Rico’s Medical Sciences Campus.

Scores of patients have been forced to delay surgeries, and doctors are “desperate to do their jobs,” said Juan Nazario Fernandez, a senior medical officer.

The San Juan hospital is a base of operations for Health and Human Services, a command center for critical and acute care. Seven regional hospitals have been deemed primary medical care hubs for the island’s more than 3 million residents.

Hospital HIMA San Pablo Caguas, about 22 miles south of San Juan, is a hub for the eastern region. A sign on the main entrance doors Wednesday indicated that just one visitor per patient would be allowed in, for security reasons. The hospital is well over its maximum capacity of 405 beds.

“Every single square foot here is being dedicated for clinical purposes. The logistics are crazy right now,” said Armando Rodríguez, the hospital’s vice president. In the emergency room, hospital beds clogged hallways. “This is not the way to run an ER.”

Gloria Dominguez, 81, had been in the emergency room since 8 p.m. the previous night, having called an ambulance because of chest pains. By 2 p.m. the next day, she had not yet been placed in a bed. Instead she had been sitting in a chair, receiving oxygen, all night and all day.

Feet away, lying in a bed surrounded by other patients, Pablo Rosario received antibiotics through an IV. After a foot of water had entered his home in Juncos, Rosario developed an ulcer on his left foot. On Sunday, he tried going to a hospital in Humacao, but the roof of the operating room had blown off. So he was transported to Caguas.

He needs surgery, but “they don’t know when” he can have it, said his wife, Liduvina Martinez Rodriguez. There are not enough beds to admit him to a room.

The hospital also was still treating 28 patients from the islands of Tortola and St. Thomas, people who had been airlifted out after being rescued in the aftermath of Hurricane Irma earlier in September.

“They opened their eyes and didn’t know they were in Puerto Rico,” said Natalia Rodríguez, a hospital staff member. Many have had no contact with family, and the hospital has been unable to communicate with its partner hospital in Tortola since Irma.

The hospital’s vice president is most concerned about the patients receiving dialysis — several times as many as the hospital usually takes in. About 140 patients were on dialysis in the Caguas hospital on Wednesday, while it usually receives about 15.

“I don’t have the space for more people,” he said. “I am very worried, not for the ones that are here. I’m worried about the ones that are not.”

But the HIMA hospital was lucky to have plenty of diesel and water reserves, Rodríguez said. It also received a large shipment of supplies that day from the National Guard. Other hospitals aren’t so lucky.

Nurses and hospital workers at Hospital del Maestro in San Juan are running the emergency room without power. (Dennis M. Rivera Pichardo/For The Washington Post)

Just before noon Wednesday, Ruben Norat Roig, administrator of Centro Médico Menonita in Cayey, was running out of diesel to run generators for his dialysis patients.

“I have enough until 3 p.m.,” he said. “I don’t have anywhere to put them.”

While a diesel truck had arrived to fuel up the generators for the main hospital, the hoses did not match up with the generators for the dialysis center. But at least the diesel distributed Wednesday would give the hospital enough fuel for three days.

“That was like winning the lottery,” he said.

Rep. Richard E. Neal (Mass.), the ranking Democrat on the House Ways and Means Committee, said Thursday that dialysis patients who can’t get proper treatment are “in dire condition due to Puerto Rico’s lack of needed fuel and supplies” and in a statement urged evacuation of patients if supplies can’t be made available soon.

“I am deeply concerned about reports from Puerto Rico that millions of people, including thousands of dialysis patients, are not receiving the urgent medical care they depend on,” Neal said. “In this day and age, no American should ever die of a manageable medical condition.”

In places outside San Juan, such as the hospital in Cayey, a near-total lack of communication has created a nightmare for doctors. The hospital’s electronic records system is down, forcing doctors to note information manually and leading visit times to double. With no phone reception, doctors can’t be on-call from their homes, so they’ve been forced to sleep in the hospital, using rooms that could house patients.

Other hospitals have struggled to contact cadaver centers, or families of the deceased, leading morgues to fill up. Marta Rivera, the head of an association of Puerto Rico hospitals and executive director of Hospital San Juan Capestrano, said she could not determine exactly what supplies hospitals across the island need because she can't contact many of the administrators.

In the Hospital de Maestro’s dark emergency room Thursday, Janet Colon Ramos lay in a hospital bed, receiving treatment for shingles. Colon Ramos — who lives in the town of Corozal, more than 20 miles southwest of San Juan — waited four days to get treatment for the virus. With no Internet service or phone reception, she didn’t know whether hospitals were open, and she didn’t want to risk running out of gas searching.

Colon Ramos had been told the shingles might have been activated by stress.

“Having to give breakfast, lunch and dinner to three kids with no water or power?” she said. “It’s stressful.”

Correction: Due to a typographical error, an earlier version of this article misspelled the name of the island of Tortola. The article has been updated.

A patient rests at Hospital del Maestro in San Juan, where there is no power. (Dennis M. Rivera Pichardo/For The Washington Post)