Rescue workers have pulled a Japanese toddler alive from under a landslide triggered by an earthquake, but his mother has been pronounced dead.
Rescuers say they were alerted by the mother's voice
Rescuers have not yet been able to free the woman's three-year-old daughter whose condition remains unclear.
The family's car was buried by a landslip sparked by a major quake which hit northern Japan four days ago.
The tremor and aftershocks have now killed 32 people. Another powerful quake shook the area on Wednesday.
No injuries have been reported so far from the latest quake, which measured 6.0, but a large building is said to have collapsed in Ojiya, northern Japan.
Efforts began in Niigata prefecture to free the Minagawa family after firefighters drafted in from Tokyo heard a voice under the rubble.
Takako Minagawa and her two children were trapped in their car
Japanese media reports said the three were alive when rescuers reached them, but officials later said Takako Minagawa appeared to have no pulse.
She and her son were airlifted to hospital. Ms Minagawa was later pronounced dead on arrival.
Her daughter Mayu is still trapped in the car.
The latest tremor to hit the area was centred on Hirokami, Niigata prefecture - the same region affected by Saturday's large 6.8 magnitude quake and its many aftershocks.
The tremor was also felt in Tokyo, where tall buildings shook.
"Aftershocks are continuing - we don't know what the damage situation is yet," AP news agency quoted Kazumasa Sakurai, an official at the Hirokami city hall, as saying.
Train and air services have been suspended, but a nearby nuclear plant is
functioning normally, local TV reported.
Since the weekend, many thousands of people in the area have been sleeping in emergency shelters and even outside for fear of further tremors, and TV pictures from the shelters showed people throwing themselves to the floor and screaming in terror as the latest quake struck.
The Japanese Prime Minister Junichiro Koizumi visited Niigata, 260km (160 miles) north of Tokyo, on Tuesday.
"I've again been made keenly aware of the need to put together response measures for both the national and local governments," he said.
Bad weather conditions - continuing rain and temperatures set to drop below freezing - have contributed to the suffering.
Authorities have also warned that there is a desperate need for food and water supplies.
The earthquakes follow a record 10 typhoons to hit Japan this year, including one that killed at least 80 people last week.