BRATISLAVA, Slovakia—Three women drowned in a flash flood as they tried to rescue dogs from an inundated animal shelter in central Slovakia, the prime minister said Thursday.

The women had responded to an emergency appeal issued Wednesday in the town of Revuca after heavy rain caused a river to burst its banks.

Identified by local media only as Zuzana, Katka and Zdenka, all 3 worked at another animal shelter in the nearby town of Roznava, 300 kilometers (185 miles) east of the capital Bratislava.

The women managed to load the dogs into their vehicle but were swept away by floodwaters on the return journey.

"The information is confirmed, all 3 women died," Prime Minister Peter Pellegrini told journalists in Bratislava.

Emergency services spokesman Erik Piater told the TASR newswire that rescuers had recovered the remains of 1 woman and were still searching for the other bodies.

Tragedy also struck in western Slovakia on Wednesday as 12 people were killed, including 4 students, when a public bus carrying school children collided with a truck loaded with rocks and soil.

The Slovak government has declared Friday a national day of mourning.