At least four people have been killed after dozens of tornadoes swept across the southern US, causing extensive property damage and leaving tens of thousands of people without power.

On Saturday and Sunday, nearly 40 tornadoes were reported in Texas, North Carolina, Louisiana, Georgia and Arkansas.

Two of the deaths took place in Mississippi, with one more each in Texas and North Carolina.

About 80 people are killed each year by tornadoes in the US, according to National Weather Service (NWS) statistics.

Mississippi Governor Tate Reeves said one of the two deaths in the state had taken place in Adams County - about 92 miles (148km) west of the city of Jackson.

The second death took place in Lowndes County on the state's border with Alabama. At least ten people were injured across the state.

As of 10:30 local time on Monday (15:30 GMT), nearly 32,000 people were still without power in Mississippi, down from about 100,000 after the storms struck over the weekend, according to website PowerOutage.us.

In Texas, a tornado watch on 28 December received a rare "particularly dangerous situation" designation from the Storm Prediction Center - a rare occurrence which takes place for only approximately 7% of tornadoes each year.

While there is no official criteria for issuing similar warnings, they are usually given when forecasters believe that multiple "strong" or "violent" tornadoes are imminent in a given area.

A 48-year-old woman was killed in Texas' Brazoria County, near the state's Gulf Coast, according to the local sheriff's office. Four people also received non-critical injuries.

In Texas' Montgomery County, north of Houston, approximately 300 buildings were damaged - including 30 completely destroyed - after tornadoes with winds of up to 145mph (233 km/h) swept through the area.

The fourth death took place in North Carolina, where the state's highway patrol said a 70-year-old man identified as Matthew Ronald Teeple was killed after being struck by a falling tree while driving.

According to NWS statistics, approximately 800 tornadoes are reported across the US in an average year, resulting in 80 deaths and 1,500 injuries.

This year, however, the US recorded 1,762 tornadoes between January and November - the most since 2011.