Contaminated fresh tomatoes served in restaurants were the cause of a recent salmonella outbreak that sickened dozens of people in 21 states, health officials said Friday.

The outbreak, now over, sickened at least 183 people, according to the Centers for Disease Control and Prevention. There were no reports of deaths, although 22 people were hospitalized. Interviews with victims, including detailed surveys of what they had eaten and where before falling sick, led investigators to suspect restaurant tomatoes as the cause.

"We have identified tomatoes eaten in restaurants as the cause of this outbreak. We don't have any information that a name or a certain type of restaurant is involved. As far as we can tell, it's across the board," said Dr. Christopher Braden, a foodborne outbreak and surveillance expert with the Food and Drug Administration has begun probing the source of the contaminated tomatoes, said Dr. David Acheson, chief medical officer of the FDA's Center for Food Safety and Applied Nutrition.

The cases of illness peaked in late September, leading officials to believe the outbreak is now over.

"We don't believe there is a need to issue a specific warning to consumers regarding the consumption of tomatoes," Acheson said.

Outbreaks of salmonella in tomatoes occur periodically. A 2004 outbreak, linked to tomatoes sold in Sheetz convenience stores, sickened more than 400 people.

The states involved in the latest outbreak are: Alabama, Arkansas, Connecticut, Georgia, Indiana, Kentucky, Maine, Massachusetts, Michigan, Minnesota, Nebraska, New Hampshire, North Carolina, Ohio, Pennsylvania, Rhode Island, Tennessee, Vermont, Virginia, Washington and Wisconsin. There also were two cases reported in Canada.

The salmonella cases came on the heels of an E. coli outbreak, caused by tainted spinach from California, that killed three people and sickened more than 200 others.