WASHINGTON — A possible E. coli outbreak from beef suspected of infecting people in nine states has resulted in at least 12 people being hospitalized, according to The Associated Press. The victims may have become ill after eating beef produced by JBS Swift Beef Co. of Greeley, Colo., the Centers for Disease Control and Prevention relayed. So far, 23 people have been reported ill; two of them suffered from hemolytic uremic syndrome.

On Sunday, JBS Swift recalled about 380,000 lbs. of beef after several illnesses were reported and a government investigation indicated a possible connection to the company's product. That recall expanded a June 24 recall of just over 41,000 lbs.

Health officials in several states investigating the strain of E. coli found most ill persons had consumed ground beef and many reported that it was undercooked, C.D.C. said. Ground beef with the strain of E. coli was obtained from the home of one person infected.

"At least some of the illnesses appear to be associated with products subject to these recalls," the C.D.C. said in a statement on its web site.

On April 2, the first reported illness became known, according to the C.D.C., and the last illness was reported on June 13. So far, Wisconsin and Michigan appear to have been the hardest hit by the outbreak, with six ill people in each state identified by the C.D.C. Other cases were reported in California, Maine, Minnesota, New Hampshire, New Jersey, New Mexico and New York.

Long-time food-safety critic U.S. Rep. Rosa DeLauro of Connecticut said this week she is concerned it took too long for JBS Swift to recall the meat. The beef was produced April 21, according to the company and U.S.D.A.

"It is deeply troubling that it has been over two months since this meat was produced and only now are we learning that thousands of Americans have potentially been exposed to E. coli-tainted beef," said Ms. DeLauro, who heads the House subcommittee in charge of Agriculture Department spending. "I urge the U.S.D.A. to aggressively and expeditiously investigate."

The Food Safety and Inspection Service initially took a sample of the beef on May 21 that tested positive for the strain, according to the agency. Because that beef did not enter the food supply, officials did not urge a recall. A follow-up investigation, including information from the illnesses reported, prompted F.S.I.S. to go to the company and request the recall, an agency spokesman said.

"Until recently, there was not adequate evidence suggesting a link between this source material and illnesses," said F.S.I.S. spokesman Brian Mabry.

JBS Swift stated it sold the meat as whole-muscle cuts, some of which may have been later ground by retailers who purchased it.