They make buildings collapse on them and causes flying debris to hit them.
Tornadoes killed 81 people in the U.S. in 2007.
Tornadoes in the U.S. killed 70 people in 2012.
85 people worldwide were killed by tornadoes in 2006, 67 of them in the U.S.
As of July 25, tornadoes in the US have killed 10 people in 2015.
Worldwide in 2011 574 people were killed by tornadoes including 553 in the U.S.
In 1990 tornadoes killed 53 people in the U.S. Figures for other countries are not available.
Tornadoes killed 30 people in the U.S. in 1995. It is unknown how many, if any, were killed by tornadoes in the rest of the world.
In an average year 60 people are killed by tornadoes and 1500 are injured in some way.
Tornadoes in 1953 killed at least 526 people. Tornadoes in the United states killed 519 people, and one in Canada killed 7. Data for other countries is not readily available.
Tornadoes kill 60-80 people in an average year.
Tornadoes killed 32 people in Tennessee in 2011.
Tornadoes don't kill people every day. On average about 80 people are killed by tornadoes each year.