Salmonella from peanut butter?

This was something I'd never heard of happening from peanut butter:

Consumers should throw away certain jars of Peter Pan and Great Value peanut butter after the spread was linked to a salmonella outbreak that has sickened almost 300 people around the country, ConAgra said.

Lids of jars produced by ConAgra Foods with a product code beginning "2111" can be returned to the company for a refund, the company said.

The salmonella outbreak, which federal health officials said Wednesday has sickened 288 people in 39 states since August, was linked to tainted peanut butter produced by ConAgra at a plant in Sylvester, Georgia. How salmonella got into peanut butter is still under investigation, said Dr. Mike Lynch, an epidemiologist at the Centers for Disease Control and Prevention.

The article confirms this is the first time there has been a reported situation with salmonella and peanut butter. They are investigating to see if they can determine how it happened. They also have not confirmed how many jars were involved in the recall.