Initially, the explosion was thought to be caused by a Japanese torpedo.

It was initially thought to be caused by ball lightning.

This was thought to be caused by an asteroid approximately 10 meters in diameter.

Their parallel nature is thought to be caused by the direction of the prevailing wind.

It is thought to be caused by spasms of the artery.

These emotional reactions are thought to be caused by the body's natural tendency to avoid disease.

Asthma is thought to be caused by a combination of genetic and environmental factors.

Both are thought to be caused by the immune system's attacking the host body.

However, these symptoms are not thought to be caused by an actual medical disorder.

They are thought to be caused by mental health problems instead.