Another strong aftershock shook central Italy late Tuesday, sending rescue crews and residents running from fragile, quake-damaged buildings.

According to the U.S. Geological Survey, the aftershock measured a magnitude of 5.6, while Italian seismologists said it measured 5.3.

The tremor sent chunks of concrete falling from buildings in the already ravaged city of L'Aquila. The ANSA news agency reported the aftershock further damaged the Chiesa delle Anime Sante, one of the town's many historic buildings.

ANSA also reported that one person was killed near the city.

The aftershock, which struck at 7:47 p.m. local time, was felt as far away as Rome, which is 110 kilometres to the southeast.

When the tremor hit, rescue crews had been digging through rubble in the hope of finding more survivors from Monday's 6.3-magnitude earthquake.

Civil protection officials in says the death toll in has reached 235 but 15 people are still missing. Among the dead were four students buried in the rubble of a dormitory at the University of L'Aquila.

Lilly Centofanti was waiting outside the dormitory Tuesday to see if rescue workers would find her 19-year-old younger brother Davide.

"There's no information," she kept telling anxious relatives calling her on her cell phone.

In Pettino, a suburb of L'Aquila, two buildings collapsed following the aftershock, according to the news agency ANSA. No one was believed to be inside either building.

Earlier on Tuesday, Italian Prime Minister Silvio Berlusconi said another 1,000 people were injured by the earthquake and at least 100 of them are in serious condition.

Berlusconi said the rescue efforts would continue for another two days, but said trapped people had diminishing chances of survival.

CTV's London Bureau Chief Tom Kennedy, reporting Tuesday from the region, said crews have been working non-stop since the earthquake struck.

"It's quite possible that large chunks of rubble could fall on the people who are trying to dig away to find anymore bodies," Kennedy said.

In Onna, Italy, a town of 300, Kennedy said all of the homes had been damaged by the earthquake. He said one in 10 people in the town did not survive.

Prime Minister Stephen Harper issued as statement on Tuesday pledging the Canadian government's support should Italy request international aid.

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

"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".

L'Aquila Mayor Massimo Cialente said every single structure in the city will have to be inspected before people are allowed to move back in.

Roughly 70,000 people live in the historic city, located in a valley surrounded by the Apennine mountains. On Monday, it was estimated that 50,000 were left homeless after the earthquake, but that number has been lowered to between 17,000 and 25,000 because many have moved in with relatives.

With files from The Associated Press