Some 200,000 Amish people live in more than 20 US states

The most conservative, Old Order groups of these reclusive, religious people drive horses and buggies rather than cars. Many have no telephones or electricity in their homes.

They send their children to private, one-room schoolhouses until the age of 13.

They eschew technology and preach isolation from the modern world. They do not join the military or accept assistance from the government.

The Amish community in Lancaster County, Pennsylvania was a model for the 1985 film Witness starring Harrison Ford, a thriller which contrasted the violent modern world with their peaceful existence.

The Amish experience many of the same problems as other communities, but keep them private.

Strict regulations

Some 200,000 Amish people live in more than 20 US states and in the Canadian province of Ontario.

FACTS ABOUT THE AMISH Anabaptist Christian denomination Communities in the US and Canada Many communities reject links to outside world Most Amish shun modern technology including electricity and cars Plain clothing - no buttons allowed in some communities Speak English and a German dialect called Pennsylvania Dutch

In pictures: School attack

The oldest group of Old Order Amish, about 16,000-18,000 people, live in Lancaster County, a rural, farming area where Amish first settled in the 1720s - many fleeing religious persecution in Europe.

The Amish are divided into dozens of separate fellowships, broken down into districts or congregations. Each district is fully independent and lives by its own set of unwritten rules, or Ordnung.

The Old Order are the most conservative of these groups, and observe strict regulations on dress, behaviour, and the use of technology, which they believe encourages humility and separation from the world.

Men and boys wear straw broad-brimmed hats

Men and boys wear dark-coloured suits, straight-cut coats and black or straw broad-brimmed hats. They grow beards only after they marry.

Modern technology is not rejected out of hand. Some farms have telephones and local groups can allow electricity to be used in certain circumstances.

Most Amish are trilingual. They speak a dialect of German called Pennsylvania Dutch at home, use High German at their worship services, and they learn English at school.

In some ways, the Amish are feeling the pressures of the modern world. Commentators say child labour laws, for example, are threatening long-established ways of life.

While many Amish own firearms, used to hunt and kill wild animals, their communities have until now been largely free of violent gun crime.