Teresa Heinz Kerry in critical condition at Nantucket hospital

Teresa Heinz Kerry, the 74-year-old wife of U.S. Secretary of State John Kerry, was hospitalized in Nantucket, Mass., on Sunday, sources told NBC News.

Sources cited an unspecified medical condition as the reason for her hospitalization. An ambulance left the Kerrys Hulbert Avenue home on Sunday at about 4 p.m. ET.

“She was brought in, in critical but stable condition, and that is currently how ... her condition still remains,” a rep for Nantucket Cottage Hospital told the Boston Globe. “At this point, we are determining the next phase of her care, be that either in our facility on the island, or on the mainland.”