LUDIAN, Yunnan ?-- A powerful earthquake jolted Southwest China's Yunnan province Sunday afternoon, killing at least 381. Following is what we know and still don't know about the disaster as of Monday morning.

-- Quake:

It struck at 4:30 pm Sunday (Beijing Time);

Epicenter was 12 km deep at Longtoushan, a township 23 km southwest of the county seat of Ludian, Zhaotong City in Yunnan;

-- Destruction:

It was the most powerful earthquake to hit Yunnan in 14 years;

It is so far the third-deadliest earthquake in China in the past six years (after 2008's Wenchuan Earthquake and 2010's Yushu Earthquake);

Over 12,000 houses toppled and 30,000 were damaged;

-- Casualties:

381 killed (302 in Ludian, 66 in Qiaojia County, 12 in Huize County, 1 in Zhaoyang District);

1,801 injured;

3 still missing;

-- Disaster zone:

Quake-prone region in northeast Yunnan;

One of the poorest areas in China;

Zhaotong's population is around 5.2 million;

Home to 23 minority ethnic groups;

-- Rescue efforts:

7,000 rescuers, including 5,000 soldiers, police officers, and firefighters, are searching the rubble and working to move the injured out of the quake zone;

Chinese President Xi Jinping urged prioritizing saving lives;

Premier Li Keqiang is en route to Yunnan to oversee quake relief;

Two military helicopters and two cargo planes are on their way to the quake zone;

Highest level of earthquake emergency response issued;

-- What is hampering rescue:

Continuous downpours (rain expected for the next four days);

Blocked roads;

Lack of professional facilities and rescue workers;

-- Potential dangers:

Rain-triggered mudslides;

Collapsing houses;

Rising "earthquake lakes" due to areas filling with water

Frequent aftershocks;

-- What is most urgently needed:

Blood;

Food and medicine;

Quilts and blankets;

Water;

Tents;

Power still out in some remote regions;

-- Still unknown:

When blocked roads will be cleared; officials said relief supplies are in stock but hard to deliver.