Washington state and local health officials are investigating an outbreak of intestinal illnesses that struck a number of people who attended a cheerleading competition in Everett last weekend.

More than 3,000 people attended, and more than 1,000 competed, in the cheerleading and dance/drill event hosted by the Washington Interscholastic Activities Association in Everett on Saturday, February 4, the Washington State Department of Health said in a news release.

Health officials said they do not know how many people were sickened, but said dozens began to suffer from vomiting and diarrhea on Sunday and Monday.

Cause and source of the illnesses have not yet been determined. State health officials say they are working with the Snohomish county Health District to investigate the outbreak, which includes sending a questionnaire to participants, as well as collecting samples for testing at the state Public Health Laboratories.

People who attended the event and have severe symptoms are advised to contact a health care provider.