How old / big are they? If still seedlings, sounds like damping off.

That's most likely damp off caused by fungi and soil that is too wet. Make sure your soil is well drained, and don't over water.

thanks for the help, BTW the plants are about 6 weeks old and 12 to 18 inch high....my raised beds have a lot of peat in them and retain water really well---will back off on the watering and maybe next year have a bed for peppers only with less peat??? thanks

Peat is very water retensive. That explains it.

It is 99% damping off fungus and as stated, over watering, by you or mother nature is the culprit.
Bruce

One option is to add lots of bark to your raised bed to improve drainage. This will make your watering less critical. May need to add lime though as this would be an acidic mix.