Tornadoes can occur at any time of year in Texas, including December, but they happen most often in spring and summer. Spokesmen for the Division of Emergency Management urged Texans to learn what to do when a tornado is sighted. The most important rule is to get low and stay low.

Here are safety tips you should follow:

		Seek shelter in an interior room on the lowest floor of the home, such as a bathroom, closet or room without windows.
		Go to an interior room or hallway on the lowest floor of the office building, or to the designated shelter area.
		Leave your mobile home and take shelter in a nearby building. If no building is nearby, lie flat in a ditch or ravine. Mobile home parks should have a designated area, as well as a monitor to track broadcasts during severe weather.
		Never stay inside a car. Leave the car and lie flat in a ditch or a ravine. If a building is nearby, take shelter inside. Never try to outrun a tornado in your car.
		At school, follow plans and go to a designated shelter area, usually the school's interior hallway on the lowest floor. Stay out of auditorium, gyms and other areas with wide, free-span roofs. If you are in a portable or manufactured building, go to a nearby permanent structure or take cover outside on low, protected ground.
		Go to the interior rooms and halls on the lowest floor of a shopping center. Do not leave the shopping center to get in your car.
		If you are in open country, take cover on low, protected ground.
		Avoid areas near exterior glass or doors, areas along exterior walls, or rooms with wide expanse roofs -- such as auditoriums, cafeterias and gyms.
		Learn the difference between a Tornado Watch and a Tornado Warning. A Tornado Watch means watch the sky. A Tornado Warning means a tornado is on the ground and you must seek shelter immediately.

	Top 10 tornadoes to strike in Texas since 1900
MAY 11, 1953 -- WACO The deadliest tornado in Texas history struck shortly after 4 p.m. on May 11, 1953. An F5, the tornado killed 114 persons and injured 597. It destroyed about 600 homes and other buildings, damaging more than 1,000. It was one-third of a mile in width. MAY 18, 1902 -- GOLIAD The second deadliest tornado in Texas struck 50 years earlier and also killed 114 persons. There were 250 injuries. It was estimated to be an F4 tornado, destroying hundreds of buildings. It was one-eighth of a mile in diameter. APRIL 12, 1927 -- ROCKSPRINGS An F5 tornado nearly one mile wide, the Rocksprings tornado struck in Edwards County. The tornado killed 74 people and injured 205, destroying 235 of the 247 buildings in the town. APRIL 9, 1947 -- THE TRI-STATE TORNADO The fourth deadliest tornado in Texas history also moved through western Oklahoma and Kansas. The funnel was reported to be between one and two miles wide. Just before crossing into Oklahoma, it destroyed the town of Glazier (near Pampa) and most of the town of Higgins. It killed 68 Texans, with 40 injured at Glazier and 232 injured at Higgins. The three-state death toll was 181, with 970 injuries. APRIL 10, 1979 -- WICHITA FALLS This 1.5-mile-wide killer was an F4, killing 42 people in Wichita Falls. It caused over 1,700 injuries, destroyed over 3,000 homes and left 20,000 homeless. MAY 6, 1930 -- FROST The F4 tornado struck the town of Frost in Navarro County, Ennis in Ellis County and several points between these two locations. The death toll from Texas' sixth deadliest tornado was 41 with 200 injuries. MAY 6, 1930 -- KARNES-DEWITT Killer tornado No. 7 occurred on the same day as the Frost tornado. The F4 tornado ran through Karnes and Dewitt counties, striking a number of homes and shelters that were not well constructed. The death toll was 36, with 60 injuries. MAY 30, 1909 -- ZEPHYR The Zephyr tornado in Brown County struck around midnight, killing 34 and injuring 70. Texas' eighth largest tornado was rated F4. MAY 22, 1987 -- SARAGOSA Also an F4, this tornado struck in Reeves County, destroying more than 80 percent of the town of Saragosa. It killed 30 residents and injured 121. At Guadalupe Hall, 22 deaths occurred during a graduation ceremony, as parents and grandparents died shielding children from debris with their own bodies. MAY 11, 1970 -- LUBBOCK The 10th deadliest tornado left an eight-mile path of destruction through Lubbock, killing 28 and injuring 500. The storm destroyed more than 1,000 homes and apartment units. It was rated F5 and was one of the key storms used in developing the Fujita scale. Information provided by the National Weather Service and the book "Significant Tornadoes 1680 - 1991" by Thomas P. Grazulis.