Numerous new cases were people who became ill two to three weeks ago, when contaminated lettuce was still being sold.
It takes two to three weeks between when a person becomes ill with E. coli and when the illness is reported to CDC. On Friday, health officials said they have learned of four more - another in California as well as one each in Arkansas, Minnesota and NY.
The patients who died were from Arkansas, California, Minnesota and NY.
The latest batch of illnesses are believed to be linked to romaine lettuce grown in the Yuma, Arizona region.
A total of 89 people were hospitalized with 26 of them having developed a type of kidney failure called hemolytic uremic syndrome.
However, the lettuce from that region is past its shelf life and is likely no longer being sold in stores or served in restaurants, the FDA said.More news: White House prepared for North Korea summit to take place June 12
Officials also noted that some of the individuals who became ill never actually consumed the contaminated lettuce but were in close contact with someone else who had done so.
Numerous new cases were people who became ill two to three weeks ago, when contaminated lettuce was still being sold. The growing season in Yuma ended April 16.
Sickness can begin three to four days after swallowing E. coli, with symptoms of diarrhea, severe stomach cramps and vomiting.
"We are actively evaluating a number of theories about how romaine lettuce grown on multiple farms in the same growing region could have become contaminated around the same time", Dr. Scott Gottlieb and Dr. Stephen Ostroff wrote.
The outbreak is the largest in the United States since 2006, when spinach tainted with a similar strain of E. coli sickened more than 200 people.