Dozens of students are sick at Hastings Elementary School in Westborough, Massachusetts, prompting the school to close Friday.
The illness emerged in the last couple of days.
"We got an email from the principal letting us know there's a virus going around," said Hastings parent Lindsay Quist. "This is one of my biggest fears. It spreads so quick."
The sickness hasn't been specifically diagnosed, but school officials say it appears to be a gastrointestinal virus, with vomiting being the main symptom. Some students were vomiting in school.
"I think maybe half his class was out," said Aidan McCann, whose son attends Hastings.
Westborough Superintendent Amber Bock says 73 students either stayed home or were sent home on Wednesday, and 53 students were out of school on Thursday.
Seven school staff members are also sick.
Any student missing the MCAS this week will be allowed to take it on another date.
Hastings is the only school in the district with so many students sick.
Custodial staff will be cleaning the building all weekend.
There are about 500 students at Hastings and 92 staff members.