Health officials in Minnesota are investigating a gastrointestinal outbreak at several dorms at the University of Minnesota, according to a Twitter post and multiple local news outlets.

As many as 28 students living in Frontier Hall fell ill earlier this week with symptoms of vomiting and diarrhea.

The Minnesota Department of Health started receiving reports about incidences on Wednesday and has suspected the illness to be norovirus. According to Doug Schultz, spokesperson of Minnesota Department of Health, they are asking questions to sick students about where and what they have been eating.

University spokesman Steve Henneberry says they’re disinfecting Frontier and three other residence halls as a precaution, including two dining halls.

In addition, he said the university has notified all students about the outbreak, and is encouraging them to be extra-vigilant about handwashing, and to not share any food, drinks or eating utensils. He says the virus typically lasts 24 hours.

Norovirus is a highly contagious viral illness that often goes by other names, such as viral gastroenteritisstomach flu, and food poisoning.

The symptoms include nausea,vomiting, diarrhea, and some stomach cramping. Sometimes people additionally have a low-grade fever,chills,headache, muscle aches, and a general sense of tiredness. The illness often begins suddenly, and the infected person may feel very sick. In most people, the illness is self-limiting with symptoms lasting for about 1 or 2 days. In general, children experience more vomiting than adults do.

Norovirus is spread person to person particularly in crowded, closed places. Norovirus is typically spread through contaminated food and water, touching surfaces or objects contaminated with norovirus and then putting your hand or fingers in your mouth and close contact with someone who is vomiting or has diarrhea.

Norovirus causes more than 20 million illnesses annually in the US, and it is the leading cause of gastroenteritis outbreaks in the United States.