Tornado loss estimate: $2 billion to $5 billion

NEW YORK (CNNMoney) -- The string of tornadoes that ripped across the central United States in the past week did between $2 billion and $5 billion in damage, according to an initial estimate from Eqecat, a catastrophe risk modeler.

The storms produced 79 tornadoes that touched down in 10 states over a three day period from May 18 through 20.

The most devastating were powerful twisters that hit south of Oklahoma City, a EF 4 storm that killed two people on Sunday, followed by an EF 5 tornado that killed 24 people in Moore, OK, on Monday. EF 5 is highest possible ranking for a tornado's power.

There were an estimated 13,000 structures damaged in the town of Moore alone, and the bulk of the losses from the storm system were concentrated there.

Eqecat's estimate is for insured structural losses and does not include the costs associated with injuries or deaths.

The firm said that so far this year, tornado activity has been below the long-term average, with only 342 tornado touchdowns to date through Thursday. That's only about one-half of the average for the same period over the last eight years.