AMATRICE, Italy — Strong aftershocks damaged two key access roads into quake-struck Amatrice on Friday, threatening to isolate the tiny hilltop town as hopes dimmed that firefighters would find any more survivors from the earthquake that killed at least 267 people.

Some crumbled buildings in Amatrice cracked even further after the biggest aftershock of Friday morning struck at 6:28 a.m., one of more than 1,000 that have hit the area since Wednesday’s quake. The U.S. Geological Service said it had a magnitude of 4.7, while the Italian geophysics institute measured it at 4.8.

The shaking ground also damaged a key access bridge to Amatrice, forcing emergency crews to close it. Mayor Sergio Pirozzi said he was working with authorities to find an alternative bypass also to another damaged bridge.

“We hope to God it works because otherwise with the damaged stretch of road, we are without any connection” to the main roads.

“With the aftershocks yesterday but especially this morning the situation has worsened considerably, so in terms of the emergency we have to make sure Amatrice does not become isolated, or risk further help being unable to get through,” he said.

Even before the roads were shut down, traffic into and out of Amatrice was horribly congested with emergency vehicles bringing hundreds of rescue crews up to Amatrice each day and dump trucks carrying tons of concrete, rocks and metal down the single-lane roads.

Multiple ambulances were also bringing the dead to an airport hangar in the provincial capital of Rieti, where four big white refrigerated trucks created a makeshift morgue to which relatives came in a steady stream Friday.

Premier Matteo Renzi has declared a state of emergency and authorized 50 million euros ($56 million) for immediate quake relief. The Italian government also declared Saturday a day of national mourning and scheduled a state funeral to be attended by President Sergio Mattarella.

The first private funeral took place in Rome on Friday for the son of a provincial police chief who was honored at one of Rome’s most important basilicas. Later Friday, one of Pope Francis’ top advisers is to celebrate a funeral Mass for seven other victims south of Rome.

Rescue efforts continued Friday, but nearly two days had passed since the last person was extracted alive from the rubble. While Renzi hailed the fact that more than 215 people had been rescued after the quake, authorities reported a steadily rising death toll that had hit 267 by Friday.

Civil protection operations chief Immacolata Postiglione still insisted Friday that the rescue effort hadn’t yet switched to a recovery mission. Rescue workers have noted that a person was pulled out alive 72 hours (three days) after the 2009 earthquake in the Italian town of L’Aquila.

“I confirm, once again as we have from the start, that the units that are doing the searches and rescues, including with dogs looking for other people trapped in the rubble, are absolutely fully active,” she said Friday.

On the ground, crews still hoped to find all those unaccounted for, though the number is still uncertain given the large number of visitors for summer holidays and an annual food festival.