Hundreds of people have sought treatment for gastroenteritis at the hospital in the city of Gostivar, just west of the capital, Skopje, this week.
The cause of the illness has not been determined, but authorities suspect contaminated drinking water and have urged residents to avoid the city's tap water.
Authorities have discovered an incorrectly installed pump at a waterworks that was illegally pumping water from the Vardar River into the drinking water pipeline, local media report. Police suspect foul play.
