L’AQUILA, Italy — Relatives of the missing watched in agony Tuesday as rescuers dug desperately by hand for earthquake survivors, jarred by a strong aftershock that drove home the continuing danger in this historic central Italian city.

The death toll from Italy’s worst earthquake in three decades jumped to 207 as bodies were recovered and identified. Tent camps housed some of the 50,000 left homeless by Italy’s worst earthquake in three decades, but many spent the night in the chill mountain air without blankets or covers.

Officials said some 10,000 to 15,000 buildings were either damaged or destroyed. Roofs were missing from modern buildings, old churches had fallen walls and parts of medieval buildings had tumbled to the ground.

Rescuers located four students trapped inside a partially collapsed dormitory Tuesday afternoon.

Tearful emergency workers declined to say whether they were alive or dead, telling reporters that doctors would have to announce that.

Chief firefighter Sergio Basti said rescue crews had to “surgically” remove big chunks of fallen masonry since the four were in a hard-to-reach spot and the building was so unstable.

Premier Silvio Berlusconi surveyed the devastated region by helicopter and said the rescue efforts would continue for two more days — “until it is certain that there is no one else alive.” Some 15 people were still missing, he said before the university students were found.

Berlusconi said that at least 100 of the roughly 1,000 injured people were in serious condition.

Overnight, rescuers pulled the bodies of two people overnight from the rubble of the four-story dormitory. They ran out, appearing confused, when the 4.9-magnitude aftershock hit at 11:26 a.m., the latest in a series of aftershocks that hit L’Aquila and 26 surrounding towns and cities in the snowcapped Apennine mountains. The aftershock appeared strongest around L’Aquila, a city of some 70,000 people.

Two buildings in the suburb of Pettino collapsed following the aftershock, the news agency ANSA reported, citing fire officials. No one was believed to be inside either building.The ground shook in the nearly town of Onna, about six miles (10 kilometers) away, but caused no panic.

Residents walked around dazed, clutching whatever heirlooms they had managed to grab from their homes before they collapsed.

“We lost 15 members of our family. Babies and children died,” 70-year-old retiree Virgilio Colajanni said as he choked back tears. Onna had about 300 residents and lost 38 to the quake.

Officials said search efforts were complicated by the fact that there was an unknown number of undocumented immigrants in Onna.

Rescuers were still trying to reach more isolated hamlets on Tuesday.

While the elderly, children and pregnant women were given priority at tent camps in the area, others were sleeping in cars or making arrangements to stay with relatives or in second homes out of the quake zone.

Berlusconi declared a state of emergency, freeing up millions in euros to deal with the disaster, and canceled a visit to Russia so he could deal with the crisis.

It was Italy’s deadliest quake since Nov. 23, 1980, when a 6.9-magnitude quake hit southern regions, leveling villages and causing some 3,000 deaths.

The last major quake to hit central Italy was a 5.4-magnitude temblor that struck the south-central Molise region on Oct. 31, 2002, killing 28 people, of which 27 were children who died when their school collapsed.

• Marta Falconi