Tokyo (CNN) At least nine people died when an earthquake shook southwestern Japan's Kyushu island late Thursday, the Kumamoto Prefecture disaster management office said.

Search crews scrambled to dig through rubble looking for people trapped under collapsed buildings.

The magnitude-6.2 quake struck near Ueki, the U.S. Geological Survey said. Dozens of smaller aftershocks followed.

"The ground shook for about 20 seconds before the 6.2-magnitude quake stopped," witness Lim Ting Jie said.

A rescue worker carries an 8-month-old girl after she was pulled from rubble in Mashiki on April 15.

A rescue worker carries an 8-month-old girl after she was pulled from rubble in Mashiki on April 15.

A man stands in front of his collapsed house in Mashiki on April 15.

A man stands in front of his collapsed house in Mashiki on April 15.

Kumamoto Castle is a major tourism destination and one of Japan's important cultural properties.

Kumamoto Castle is a major tourism destination and one of Japan's important cultural properties.

A woman rides a scooter in front of a collapsed house in Mashiki on April 15.

A woman rides a scooter in front of a collapsed house in Mashiki on April 15.

A man takes a picture of a damaged stone wall at Kumamoto Castle, in the city of Kumamoto, on April 15.

A man takes a picture of a damaged stone wall at Kumamoto Castle, in the city of Kumamoto, on April 15.

A woman cleans up in front of her collapsed house in Mashiki on April 15.

A woman cleans up in front of her collapsed house in Mashiki on April 15.

A road damaged by the 7.0 magnitude earthquake is seen on April 16 in Mashiki, Kumamoto, Japan.

A road damaged by the 7.0 magnitude earthquake is seen on April 16 in Mashiki, Kumamoto, Japan.

Medical staff prepare to evacuate patients from the hospital in Kumamoto City on April 16, over fears it could collapse as a wave of aftershocks hit the area.

Medical staff prepare to evacuate patients from the hospital in Kumamoto City on April 16, over fears it could collapse as a wave of aftershocks hit the area.

A severely damaged building in Kumamoto leans to one side on April 16 after the earthquake.

A severely damaged building in Kumamoto leans to one side on April 16 after the earthquake.

Rescue workers take care of a woman suffering from shock at the evacuation center at the Mashiki Town Gymnasium on Saturday, April 16, in Kumamoto, Japan.

Rescue workers take care of a woman suffering from shock at the evacuation center at the Mashiki Town Gymnasium on Saturday, April 16, in Kumamoto, Japan.

The tremors appear to have caused extensive damage, overturning cars, splitting roads and triggering a landslide, as shown by CNN affiliate TV Asahi footage.

The tremors appear to have caused extensive damage, overturning cars, splitting roads and triggering a landslide, as shown by CNN affiliate TV Asahi footage.

Residents look for an access to their homes on a road blocked by a collapsed house in Mashiki on April 16.

Residents look for an access to their homes on a road blocked by a collapsed house in Mashiki on April 16.

Evacuees wait for food at an entrance of the Kumamoto City Hall on April 16.

Evacuees wait for food at an entrance of the Kumamoto City Hall on April 16.

Damaged houses are seen after an earthquake in Mashiki. "This is the worst thing that could happen to us," said Shigeru Morita, an official in the town.

Damaged houses are seen after an earthquake in Mashiki. "This is the worst thing that could happen to us," said Shigeru Morita, an official in the town.

A rescue team removes a man from his damaged house house on April 16 in Kumamoto.

A rescue team removes a man from his damaged house house on April 16 in Kumamoto.

Students and soldiers unload food from helicopters at the isolated Tokai University campus on April 17.

Students and soldiers unload food from helicopters at the isolated Tokai University campus on April 17.

A road collapsed in a landslide caused by earthquakes in Minamiaso on April 17.

A road collapsed in a landslide caused by earthquakes in Minamiaso on April 17.

Soldiers search for survivors at a collapsed apartment in Minamiaso on April 17.

Soldiers search for survivors at a collapsed apartment in Minamiaso on April 17.

Residents walk down a street on April 17 surrounded by destroyed homes in Mashiki, Japan.

Residents walk down a street on April 17 surrounded by destroyed homes in Mashiki, Japan.

Police officers conduct a search operation at the site of a landslide caused by the quake in Minamiaso on Sunday, April 17.

Police officers conduct a search operation at the site of a landslide caused by the quake in Minamiaso on Sunday, April 17.

Vehicles line up to refuel at a gas station in Aso, Japan, on April 18.

Vehicles line up to refuel at a gas station in Aso, Japan, on April 18.

Japan Self-Defense Forces prepare relief supplies delivered by a U.S Marine Corp Osprey on April 19 in Minamiaso.

Japan Self-Defense Forces prepare relief supplies delivered by a U.S Marine Corp Osprey on April 19 in Minamiaso.

Rescuers prepare to remove the body of a woman found in a house destroyed by a mudslide in Minamiaso on Tuesday, April 19, in the aftermath of a 7.0-magnitude quake on Kyushu Island. The same region was hit by a 6.2-magnitude quake on Thursday, April 14.

Two deaths occurred in Mashiki, the Kumamoto Prefecture office said. One person died in a collapsed house, and the other died in a fire caused by the quake. Journalist Mike Fern told CNN that scores of buildings had either collapsed or caught fire, while the tremors triggered landslides, tore up roads and in one case, derailed a bullet train.

Nearly 800 people were injured, 50 severely. The prefecture office said 44,449 people had evacuated.

Prime Minister Shinzo Abe told parliament early Friday that he'd mobilized 3,000 members of Japan's Self Defense Force, police and fire service to join the rescue effort overnight. He said the government is "racing against the clock and will provide more personnel if necessary."

More shocks

Gen Aoki, director of the Japan Meteorological Agency's earthquake division, warned more aftershocks could occur over the next week.

"This is an earthquake that is going to shake for a long time," CNN meteorologist Chad Myers said.

That could mean many more building collapses.

"The buildings that were damaged in the original shock have now been redamaged or reshaken," he said. "And all of a sudden you have a cracked building, and it wants to fall down with the second shake."

Robert Geller, a seismologist at Tokyo University, said the quake increases the likelihood of eruptions from Mount Aso, Japan's largest active volcano -- though there have been no reports of extra activity, according to the Meteorological Agency.

Huge impact

An estimated 750,000 people felt "violent to severe shaking," Myers said.

"The strongest shaking was right where the most people live" in the area, he said.

A derailed Kyushu shinkansen, or bullet train, in the city of Kumamoto.

While the magnitude might not seem extreme, the shallow depth of the quake -- just 10 kilometers (6.2 miles) -- is significant.

"When you have a shallow earthquake, such as this one is, you have the potential for more damage because the shaking is close to the surface," John Bellini of the U.S. Geological Survey said.

In addition to destroying 19 houses, the quake hurled items off store shelves and littered streets with rubble.

But there's one bit of good news: The quake was centered mostly under land, not an ocean, meaning it did not spawn a major tsunami.

Regulators also moved to allay fears around the country's nuclear plants, with the country's only facility currently online in Sendai unaffected. The Genkai plant, which is located on Kyushu, also reported no problems.

CNN Map

A high-risk area

Japan, which sits along the so-called Ring of Fire, is no stranger to earthquakes.

The largest recorded quake to hit Japan came on March 11, 2011, when a magnitude-9.0 quake centered 231 miles (372 kilometers) northeast of Tokyo devastated the country.

JUST WATCHED Remembering Japan's 2011 earthquake disaster Replay More Videos ... MUST WATCH Remembering Japan's 2011 earthquake disaster 01:30

That quake triggered a massive tsunami that swallowed entire communities in eastern Japan. It caused catastrophic meltdowns at the Fukushima Daiichi nuclear power plant.

The disaster killed about 22,000 people -- almost 20,000 from the initial quake and tsunami, and the rest from health conditions related to the disaster.

Jie said Thursday's quake gave him a new appreciation for life.

"This experience has helped me to treasure my family members and relatives even more, and not take what I have and the people who support me for granted."