Before dawn on Saturday, Abood Okal and his family received the news they had desperately been waiting for. Okal and his wife and their 1-year-old son were finally offered a possible way out of Gaza - and back to their home near Boston.

An email from the U.S. State Department told them the sole border crossing with Egypt “may be open” for a five-hour window later that day, from noon to 5 p.m.

“If you wish to leave Gaza you may want to take advantage of this opportunity,” the message said.

On Saturday morning, Okal and his family went to the Rafah crossing only to find it closed. There were no officials on the Palestinian side of the crossing except for a few plainclothes security guards whose job was to keep people from getting too close to the gate, Okal said.

The U.S. government had negotiated a deal to allow American citizens to leave Gaza and cross into Egypt during the five-hour window, U.S. officials said Saturday. But Palestinian and Egyptian officials failed to communicate about opening it, an official at the border said. By the end of the day, no one had been able to cross.

Wael Abu Omar, the Palestinian spokesman for the Rafah crossing, said Palestinian officials had not had any communication with their counterparts on the Egyptian side. Egyptian media outlets reported that Cairo would only allow foreigners to cross the border if aid shipments could be delivered to Gaza.

Israel, meanwhile, has said it would strike any trucks coming across the border, especially trucks carrying fuel, according to a diplomatic official who, like others, spoke on the condition of anonymity because the official was not authorized to discuss sensitive negotiations.

Officials are discussing the possibility of setting up a screening mechanism that would allow the Israelis to inspect goods in each vehicle entering Gaza, the diplomat said. Another official familiar with the talks over the aid deliveries said any agreement would require “Israel to stop bombing the enclave for a few hours.”

The confusion and uncertainty surrounding the Rafah crossing comes as hundreds of thousands of people have fled their homes in northern Gaza in response to an evacuation order from Israel’s military, ahead of a possible ground invasion into the besieged enclave.

An estimated 500 to 600 Palestinian Americans like the Okal family are in Gaza. With no way out, families have pleaded for help from U.S. officials.

In a statement, a State Department spokesperson said the U.S. government is working to secure the safe exit of U.S. citizens from Gaza.

“We have informed U.S. citizens in Gaza with whom we are in contact that if they assess it to be safe, they may wish to move closer to the Rafah border crossing,” the spokesperson said, adding that “there may be very little notice if the crossing opens and it may only open for a limited time.”

President Biden, in a call Saturday with Israel Prime Minister Benjamin Netanyahu, discussed coordination with the United Nations, Egypt, Jordan, Israel and others in the region to “ensure innocent civilians have access to water, food, and medical care,” according to a readout from the call.

U.S. officials have spent the past several days trying to evacuate all U.S. staff in Gaza, a group of about 15 Palestinians that includes three U.S. government employees who work for USAID in Gaza, along with their immediate family members, according to a diplomatic official familiar with the situation.

Each time, they’ve been stopped at checkpoints near the border inside Gaza and have been unable to leave. In some cases at these checkpoints, the diplomatic official said, people identifying themselves as Hamas have said none of them will be able to leave until aid trucks enter the Gaza Strip.

Canadian officials also told citizens on Friday that the Rafah crossing might open Saturday for a five-hour window to allow Canadians to exit. Foreign Minister Mélanie Joly told reporters Saturday that the “latest information” she had was that “violence” in the area forced authorities to cancel the operation. She did not elaborate.

On Friday, Okal and his extended family had rushed south from Jabalya in the north of Gaza after the Israeli army ordered more than 1 million people to evacuate. They scrambled frantically to find cars to fit them all and a place to stay near the crossing.

Okal, 36, and his family spent hours waiting under the hot sun Saturday. He said there were several hundred people there, including another American family from New Jersey. He said there were other foreign nationals too, including Canadians, Swedes, Spaniards and Norwegians.

As the day dragged on, his wife, Wafaa Abuzayda, took their exhausted toddler, Yousef, back to the home where they are staying with 30 other people, a short drive away. Food vendors near the crossing warned Okal that it was not safe to stay once the sun set. Still, he remained there until nearly 6 p.m., he said, hoping something might change. When he began to hear the sound of fighter planes and drones, he knew he had to leave the area.

Kareem Fahim in Beirut; John Hudson in Riyadh, Saudi Arabia; and Amanda Coletta in Toronto contributed to this report.

previous coverage

• Israel preparing for ‘significant’ Gaza ground operation
• Inside the Israel-Hamas information war, from insider attacks to fleeing leaders
• Hundreds of thousands flee south in Gaza after Israel orders evacuation