Kosovo’s authorities say they have cut off the water supply to tens of thousands of people in the capital, Pristina, after police arrested three people on terrorism charges close to an artificial lake.
Police said officers patrolling the Badovac Reservoir saw the three unidentified men behaving suspiciously.
Pristina's water supply firm said the water-treatment facility at Badovc Lake was turned off after the arrests and that samples were being tested for any suspicious substances.
The reservoir supplies nearly half of Pristina, a city of more than 200,000 people.
Two other suspects were later arrested.
All five face terrorism charges.
A police source was quoted as saying two of the suspects were detained last year on suspicion of traveling to Syria.
Officials say more than 200 people from Kosovo have traveled to fight in Syria and Iraq, where large swaths of territory are controlled by the Islamic State extremist group.