Boston College says several of its students, including members of the men's basketball team, complained of gastrointestinal symptoms after eating at a Chipotle restaurant in Boston.
The news sent the restaurant's shares broadly lower on Monday, as investors feared an outbreak that originated in other states could take a toll on Chipotle's sales.
The college, in a statement, said it had notified the state Department of Public Health, which is trying to determine if it is part of an ongoing national outbreak of e-coli that has been linked to the Chipotle chain.
A spokesman for the state agency said it appeared that more than 20 students were sickened, but it had not yet determined the cause of the illnesses.
In a statement, Chipotle said that "the safety and well being of our customers is always our highest priority, so our restaurant at Cleveland Circle in Boston is temporarily closed while we work with local health officials to investigate a number of illnesses among Boston College students."
It added: "We do not have any evidence to suggest that this incident is related the previous E. coli incident. There are no confirmed cases of E. coli connected to Chipotle in Massachusetts."