L'AQUILA, Italy - Strong aftershocks Tuesday sent a fresh wave of fear across earthquake-shattered central Italy, and rescue crews pulled a young woman alive from a collapsed building about 42 hours after the main quake struck the mountainous region.

Eleonora Calesini, a 20-year-old student, was found alive in the ruins of the five-storey building in central L'Aquila, said her grandfather, Renato Calesini, in the seaside town of Mondaini.

"She's safe!" he told The Associated Press, adding that her father had gone to devastated city in the snowcapped Apennine mountains to try to locate the student, who wears a hearing aid. She reportedly had an arm injury but was in good condition otherwise.

The death toll from Italy's worst earthquake in three decades climbed to 235, with 15 still missing, civil protection officials said. The dead included four students trapped in the rubble of a dormitory of the University of L'Aquila, the ANSA news agency reported.

Rescue crews gave up gingerly removing debris by hand and brought in huge pincers that pulled off parts of the dorm roof, balconies and walls, showering debris down.

"Unless there is a miracle, I've been told (by rescuers) that they probably are dead," university rector Ferdinando Di Orio said.

A strong aftershock at 7:47 p.m. rained debris on screaming residents and rescue crews, who ran from the site.

"I want to go home! I want to go home!" screamed a woman identified only as Patrizia after chunks of facade rained down on them from a badly cracked building.

Her hands trembled as rescue workers gave her a cup of water. Her boyfriend, Agostino Paride, 33, an engineer, said they had driven to L'Aquila from Civitella Rovedo, some 70 kilometres away, to bring food and clothes to relatives in a tent camp.

To shelter the homeless against another chilly night in the mountains, some 20 tent cities sprouted in open spaces around L'Aquila and surrounding towns. Field kitchens, medical supplies and clowns with bubbles -- to entertain traumatized children -- were brought in.

Officials estimated Monday that 50,000 people had been left homeless by the quake. By Tuesday evening, that number was lowered to between 17,000 and 25,000, because many moved in with friends or relatives.

"I don't know how I'll make it," a dazed Pierina Diletti said as she stood in slippers and her nightgown outside her tent.

Prime Minister Silvio Berlusconi, who visited one of the encampments, said an estimated 14,500 people were being sheltered in the blue tents.

Officials said some 10,000 to 15,000 buildings were either damaged or destroyed in the 26 cities, towns and villages around L'Aquila, a picturesque city of 70,000. Teams planned to begin surveying those buildings still standing on Wednesday to see if residents could move back in.

"The assessment will concern every room, every slit, every crack," Berlusconi told a news conference, adding that assessments of the region's prized cultural treasures -- churches, monuments and other historical sites -- would begin soon.

Berlusconi surveyed the devastated region by helicopter and said rescue efforts would continue for two more days -- "until it is certain that there is no one else alive." At least 100 of about 1,000 injured people were in serious condition, he said.

In Ottawa, Prime Minister Stephen Harper said Canada stands ready to support the government of Italy should it request international assistance.

"On behalf of all Canadians, I share the profound sadness of the people of Italy at this difficult time," he said in a statement.

"Our thoughts are with those who have lost loved ones, and our prayers are with those who are still missing. The deep solidarity of Canada with Italy at this time of national grief reflects the strong friendship and ties between our two countries".

Meanwhile, a fundraising campaign is underway in Canada to assist earthquake victims in Italy.

It's being organized by the National Congress of Italian-Canadians. An official said funds raised by the group will be directed to the Red Cross to help with reconstruction in the affected area.

Experts say the vast majority of buildings in the most vulnerable regions of earthquake-prone Italy don't meet modern seismic safety standards.

Nearly half of Italy is labelled "dangerous" in terms of seismic activity, according to a 2008 report by Enzo Boschi, president of the National Institute of Geophysics and Vulcanology, and other Italian geologists and civil protection experts. But only 14 per cent of buildings in that vulnerable swath were built to seismic-safety standards, the report said.

In the seaside town of Pescara, 16 families were sheltered at the Hotel Ambra, which offered free rooms to quake victims. "They are a little traumatized," hotel business manager Vincenzo Traversa said. "It is not a beautiful experience."

So far, 6,500 hotel beds across the Abruzzo region were made available and 4,000 filled by Tuesday afternoon, said Emilio Schirato, president of Abruzzo's hotel association. Schirato said the rooms were made available "spontaneously" by hotel owners as a gesture of solidarity.

But some people pretending to have lost their homes had sought to get free hotel rooms, Schirato said. Carabinieri police were trying to verify that people being housed were in fact deserving, he said.

In L'Aquila and surrounding towns, many took shelter in their cars.

"It was a bad night," said Francesco Marchi, 18, who slept in his car with his brother in a piazza far from buildings, fearing falling debris from aftershocks. "It was really cold, but we had sleeping bags."

Two buildings in the suburb of Pettino collapsed following one aftershock, ANSA reported, citing fire officials. No one was believed to be inside either building.

The ground shook in the nearly levelled town of Onna, about 10 kilometres away, but caused no panic. Onna residents walked around dazed, clutching whatever heirlooms they had managed to grab before their homes 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 40 to the quake.

Civil protection Maj. Cristina DiTommaso, who was helping co-ordinate the rescue in Onna, said search efforts were complicated by an unknown number of undocumented immigrants living there. Most of Italy's illegal immigrants are from Romania, the former Yugoslavia or northern Africa, and many work in the largely agricultural area as farm or manual labourers.

The main quake -- which struck just after 3:30 a.m. Monday -- registered magnitude 6.3, the U.S. Geological Survey said. Italy's National Institute of Geophysics, using the Richter scale, put it at 5.8.

It was Italy's deadliest quake since Nov. 23, 1980, when a 6.9-magnitude quake hit southern regions, levelling villages and killing about 3,000.

-- With files from The Canadian Press.