GAZIANTEP, Turkey — As aid workers rushed around Syria's Idlib province in recent days to help its war-battered people survive, a Syrian relief agency was scrambling to save another struggling group: its own employees.

They have been left homeless and in search of cover from a brutal winter and an unforgiving military advance against the last pocket of rebel resistance to Syria's government after nine years of war.

Nearly a third of the 1,000 staff members or volunteers working for the organization, Ihsan Relief and Development, have been displaced by fighting over the past few months, said Baraa Al-Smoudi, the group's executive director. But there was nowhere to put them, as desperate civilians filled apartment blocks, mosques and sports halls and even took shelter under trees.

“We are thinking of building a camp,” Smoudi said.

It was the latest measure of the misery in Idlib, where hundreds of people have been killed and nearly 1 million residents uprooted during a rapid military offensive by Syrian government forces backed by air power from their ally, Russia.

The global response to the humanitarian catastrophe in Idlib relies almost entirely on Syrian aid workers, to feed people, tend to the injured and find shelter for the displaced.

But as suffering has spread in northwest Syria — with a speed and ferocity that few had anticipated — the aid workers have been just as vulnerable as the people they serve.

Paramedics have been killed after freeing survivors from rubble. Shelling or airstrikes have injured doctors and nurses during their rounds. Homeless aid workers have slept in their offices as towns emptied and their families fled, staying behind to help stragglers or the stubborn.

“The people who help people need help,” Smoudi said.

Relief efforts have been stymied by ongoing security concerns, the struggles of the Syrian aid workers and “the sheer magnitude of the humanitarian needs which continue to rise by the minute,” said David Swanson, spokesman for the U.N. Office for the Coordination of Humanitarian Affairs in Gaziantep, a Turkish city near the border with Syria.

The United Nations is “completely dependent on more than 10,000 aid workers in Idlib, many of whom themselves have been displaced,” Swanson said. “If they are not working, it undermines the overall response.”

The magnitude of the crisis has seemed to grow, exponentially, every week.

The most recent U.N. tally said that 900,000 people have been displaced in Idlib and areas of Aleppo since Dec. 1. Among them were 500,000 children, according to UNICEF.

At least 299 civilians have been killed since the beginning of the year, with 93 percent of the deaths caused by Syrian government forces, the United Nations said. At least 77 children were killed or injured in the same time period, UNICEF said, while many believe the number may be significantly higher.

The crisis has reached a “horrifying new level,” Mark Lowcock, the U.N. undersecretary for humanitarian affairs, said in a statement Monday. Families who are fleeing “indiscriminate” ­violence are “traumatized and forced to sleep outside in freezing temperatures because camps are full,” he said.

“Mothers burn plastic to keep children warm. Babies and small children are dying because of the cold.”

The relief operation is sizable, he added, but it also is overwhelmed.

Aid agencies and Idlib’s residents had long braced for a calamity.

The government of Syrian President Bashar al-Assad has vowed to retake all the country’s remaining rebel-held territory and defeat opposition militias in Idlib, including extremist militants linked to al-Qaeda who largely control the province.

By the time the latest government offensive started, in December, there were more than 3 million people in Idlib, including hundreds of thousands of people who had been displaced from other parts of Syria.

Over the past few weeks, the Syrian army has stormed up Idlib’s eastern flank, sending a mass of terrified residents fleeing air and artillery strikes headed toward the Turkish border.

The movements of people have been seismic: On Tuesday, Turkey said 150,000 people had surged toward the frontier in a six-day period.

As they navigated battlefields and sought out settlements of the dispossessed, the Syrian aid workers enjoyed few of the trappings commonly associated with large-scale international relief efforts.

They did not travel in convoys of armored vehicles. There were no specially chartered planes to whisk them to the crisis zone or away from the violence.

The trials faced by one Syrian aid organization, Violet, were typical.

During a previous government offensive, in June, three of the group’s paramedics were killed, along with a patient, when an airstrike hit their ambulance in the town of Maarat al-Numan, according to Kutaiba Sayed Issa, Violet’s general manager.

In the current crisis, Violet staff members and volunteers have been displaced, including a man who was responsible for securing housing for some 7,000 displaced families.

“He knew every empty house,” Issa said. “Now this guy is in a tent.”

Half a dozen aid agencies said that scores of their volunteers or employees had become homeless.

International organizations were affected as well.

At least 15 percent of Syrian staff members working for the International Rescue Committee have been displaced, according to Misty Buswell, the Middle East policy director for the group.

Because of the “insecurity, and the closeness of the front lines to the aid effort,” the group and its partners have been forced to suspend activities at some relief facilities and move ambulance fleets.

A recent effort by the group to register aid recipients was suspended because of nearby shelling, Buswell said.

Most of the Syrian employees have continued their aid work, picking up where they left off in the areas where they have settled, she said. Their perseverance, she said, “still gives you some kind of hope.”

But the work is becoming more grueling by the day.

Doctors now struggle to treat patients after dozens of hospitals and other health facilities were destroyed, damaged or abandoned. There are shortages of medicine and medical supplies as well as facilities for specialized care. Idlib has only one cancer center, and as the security situation worsened, it was difficult for many patients to reach it, said physician Mazen Kewara of the Syrian American Medical Society.

Some of the nearly 2,000 doctors and other medical personnel who work for the group have been displaced, and “it is not easy to find them,” he said. “It’s the worst situation I’ve faced in eight years.”

Abdulrahman Abdo Al Yahya, who lived in Idlib city and worked with Sadad, another aid organization, said traveling across the province had become impossible because of the roads clogged with people fleeing for safety.

“Every day we go out. From Maaret Misreen to Hazano, it takes four hours,” he said in a telephone interview. The distance between the towns is five miles.

Sometimes, government forces shelled the road.

“The need is very big, and we are only able cover a small part,” he said, calculating that 82,000 families do not have tents or mattresses.

“They need more blankets. I mean, we need everything,” Yahya said.

Unusually frigid conditions had made matters worse.

“It’s too cold. For the last four days, it has been unnaturally cold,” he said.

Few people have heaters. “You cannot imagine,” he said. “God help those people.”

Yahya, as an afterthought, said he and his family had been displaced twice.

Saeed Eido in Gaziantep and Sarah Dadouch in Beirut contributed to this report.