Chipotle founder and co-CEO Steve Ells says he is "deeply sorry" about the customers who were sickened after eating at the chain in recent weeks.

"They're having a tough time and I feel terrible about that," Ells said in an interview on NBC's Today show. He repeated the company's pledge to tighten food-safety procedures to ensure such incidents do not happen again.

Boston College, meanwhile, raised the number of students who have reported feeling ill after a group of them ate at Chipotle, to 141, from 120. The school said 12 of them did not eat at the restaurant.

Sales at Chipotle Mexican Grill Inc. have been slammed by high-profile food scares in recent weeks.The ingredient that sickened people has not been identified. But Chipotle says whatever the likely culprit was is out of its restaurants. The company has noted the exposure period for the outbreak appears to have passed. - AP