NAZARETH, Israel — Their mobile phones began to ring with a desperate insistence a day after the attack, as the first calls came from Syria to Jordan to Israel, where a branch of the scattered Waked family resides.

Walid Gazi Waked wrote down names, and then more names. When the Nazareth resident was done, the extended clan had lost 21 members to a suspected chemical weapons attack Wednesday in a run-down and religiously conservative town called Zamalka, just a few miles east of Syria’s capital, Damascus, in the front lines of the country’s civil war.

The tally for the Wakeds was 12 women and girls and nine men and boys killed, according to the family. Fifteen others were sickened by gas. Five are in critical condition in Syrian hospitals, the family said. Among the dead, the oldest was 68, and the youngest was 10 or 11.

Just how many were killed or injured in the attack in Zamalka and surrounding towns on Wednesday remains unverified.

Many Syrian activists put the death toll at well over 1,000. A list of the dead contains 374 names documented with images. Activists said they just couldn’t keep up with the pace of the deaths and, as many of the victims were in nightwear, there was no way of identifying them.

The group Doctors Without Borders said medics in the three hospitals it supports in the area reported 355 deaths, after 3,600 people with neurotoxic symptoms were admitted within three hours Wednesday morning.

Jamal Waked said that because the bodies were quickly shrouded, as religious custom demands, and buried within a few hours, amid chaos and the fear of more attacks, Waked elders in Syria are worried that some of the victims could have been comatose but alive when put in the ground.

“Now they will not bury anyone before a doctor examines them, just to make sure,” said Waked, gathered with relatives and friends for a three-day period of mourning in Nazareth. Sitting on plastic chairs beneath a blue tarp, smoking and drinking coffee, family members wondered exactly what happened.

Waked family members in Israel said they were told that their relatives died from chemical weapons and not conventional arms, as the bodies were intact, but they did not have evidence to support that claim.

The Waked clan was originally settled in al-Mujaydil, a Palestinian village south of Nazareth that lies abandoned and partly absorbed by the Israeli town called Migdal Ha’Emeq.

In the aftermath of the 1948 Arab-Israeli war, many of the Wakeds, who now number several thousand, escaped to Syria, where they consider themselves Palestinian refugees to this day, a part of Syrian society but still separate.

Zamalka is now virtually deserted, activists say, as families that had braved the air raids and artillery in the past months fled in terror after the suspected chemical weapons attack.

Over the past 2½ years, many of its residents had fled the town, which even before Wednesday had suffered for its support of the Syrian revolution. Videos posted online show its battle-scarred streets.

Residents say that it was 2:20 a.m. when the first rocket hit Zamalka and that five more followed.

“They made a white-blue explosion,” said Zidan al-Sabah, an activist who lives about a half-mile away.

It was not long before the field hospitals were crammed with victims vomiting and struggling to breathe, he said. In the days since, activists have gone house to house in deathly quiet streets, discovering entire families, like the Wakeds, wiped out.

“Many made the mistake of going to the basements,” Sabah said, adding that those who did increased their chances of succumbing to the toxic gases, which being heavier than air sank lower.

Other victims rushed out of their neighborhoods to receive treatment. Activists say that it is impossible to break down how many died in what area but that Zamalka is suspected of paying the highest price.

“We have lost loved ones, we lost our children and our grandfathers. We cannot comfort them. We cannot see them. We cannot assure they receive a proper burial. We are not talking about one or two, which would be a tragedy, but 21 people! That is not a family, that is a neighborhood,” Ahmed Mustafa Waked said.