STAFFORD, Va. (DC News Now) — Stafford County Public Schools shared an update regarding the illness outbreak that affected more than 1,000 students.

A deep cleaning is underway on school premises, according to the statement provided to DC News Now on Monday. Cleaning is expected to continue daily while investigations take place into the source of the outbreak.

School officials said they ruled out drinking fountains and school meal services as potential sources.

The Virginia Department of Health and the Rappahannock Area Health Department identified a number of students who tested positive for influenza. The primary symptoms reported are gastrointestinal, and while some cases are confirmed to be flu, it is not clear at this time if any other diseases are responsible for the outbreak of sickness.

Stafford County Public Schools reported only 670 students absent on Monday. While schools remain open with precautions in place, all sports and activities have been canceled.

The school division said reinstating activities would be re-evaluated later in the week.