The situation has grown more desperate by the hour in Venezuela as people dig through the rubble of collapsed homes and apartment buildings three days after the devastating one-two punch of 7.2 and 7.5-magnitude earthquakes, knowing time is running out to find survivors.

Venezuelans took the search for missing loved ones into their own hands, citing a scarcity of government rescuers, as the human toll of Wednesday’s quakes climbed to at least 920 dead and more than 51,000 missing. People reported seeing few state rescue teams in the hardest-hit areas, despite authorities projecting an image of a robust government response.

Authorities announced Friday night that they would block access to La Guaira, the epicenter of the destruction, as chaos and traffic were hampering search efforts. Officials said anyone who wants to enter would now have to seek official permits, but provided few details of who would be allowed in. More than 14,000 members of the military and police are patrolling the area, acting president Delcy Rodríguez said on state television Saturday.

Venezuela’s government said 1,600 members of foreign rescue teams had arrived to help search for survivors of the devastating twin earthquakes, which killed more than 900 people this week, as it tightened access to the worst-affected state.

Aid agencies consider the first 48 to 72 hours to be a crucial time frame to retrieve people alive, though that can be extended if they have access to food and water.

“Each person saved is a miracle,” said Jorge Rodríguez, president of the National Assembly. “We are not going to hide absolutely anything about the magnitude of this tragedy.”

In the state of La Guaira, just north of the capital, Caracas, Nazareth Jiménez sobbed into a loved one’s shoulder as she watched neighbors use hammers and power tools to try to cut through slabs of concrete in a building reduced to a mountain of debris. She was wracked with anxiety as she waited to see if her siblings, nephews, nieces and friends would emerge alive.

“My God,” Jiménez murmured, “how are we going to get them out of there?”

“We’re making a call for help to the government and countries across the world,” she said, pleading for machinery capable of moving collapsed structures. “There are still people alive in there.”

Government forces distributed food and water to survivors in La Guaira, and Rodríguez said her government was mounting a full response during these “critical hours for rescuing people alive.”

The disaster poses a huge challenge for Rodríguez, the former vice president who took office in January after the capture and removal of then-President Nicolás Maduro by the United States. Venezuela has been facing economic disarray for more than a decade, and many people reject the legitimacy of the political movement Rodríguez represents.

The number of dead was expected to climb, and people reported tens of thousands of missing on independent digital databases. Those figures likely included people who have been incommunicado due to the lack of cellphone signals, and some reports may be duplicates.

The number of injured was more than 3,300 as of midday Friday, and authorities said they rescued 243.

The International Organization for Migration said up to 6.76 million people could be affected, some 2 million of them in Caracas alone. The destruction was amplified by the quick succession of shallow quakes, experts said.

Loyce Pace, the International Red Cross regional director for the Americas, said “people are still terrified to re-enter what were their homes.”

Indeed, many continued to sleep on the street.

Omar Reyes said around 20 family members died.

“I’ve been left alone in this life,” Reyes said, walking through the rubble where two of his children were buried.

In the city of Maiquetia, people lined up outside stores and pharmacies that served them one by one behind closed doors. At one point, a woman in a crowd threw herself to the ground to protect a package of diapers with her body, desperate to keep it.

Traffic and throngs of motorcyclists at times disrupted search efforts. Mexican soldiers and volunteers repeatedly asked for silence to try to hear signs of life under the rubble, but bikers — civilian and uniformed — continued to honk horns and rev engines to the first responders’ frustration.

Some people began to carry off basic goods such as toilet paper and food from stores in Catia La Mar, adjacent to the country’s main airport. Others swarmed a civilian pickup truck that was giving out bread and water, until a soldier intervened. The parking lot of a pharmacy turned into a makeshift shelter with tarps, hammocks and tents.

A few miles away, Yuleidy Cadenas, 28, stood across the street from a collapsed public housing building, hoping her son, mother and brother would be pulled out alive.

She fled barefoot from another building as it collapsed Wednesday and found her mother’s 12-floor apartment tower had pancaked.

“I got on top of the rubble and told them to yell back, and nobody did, not my brother, nor my son or my mother,” Cadenas said.

Acting President Rodríguez said she spoke to U.S. President Donald Trump and Secretary of State Marco Rubio on Friday and they reaffirmed their commitment to send rescue teams and aid equipment.