BELGRADE, Serbia - Two people drowned in Serbia and the country declared a national emergency Thursday as rain-swollen rivers across the Balkans flooded roads and bridges, shut down schools, and cut off power. Hundreds of people had to be evacuated.

In Serbia and neighboring Bosnia, meteorologists said the rainfall was the most since measuring started 120 years ago. Belgrade authorities say the average rainfall of a two-month period hit the city in just 40 hours.

"What we are facing is the biggest water catastrophe in Serbia's history," Prime Minister Aleksandar Vucic said as his government appealed for help from the European Union, Russia, and neighboring countries.

Surging water coursed through towns and villages, overflowing across streets and into homes, sweeping bridges off their moorings. Sodden hills crumbled into landslides. Dozens of buses and cars were stranded on flooded roads and two main north-south railway lines in Serbia were impassable.

River levels rose all over Bosnia, including the capital Sarajevo. Maglaj, 60 miles north of the Bosnian capital, was cut off by water surging into streets. Some 6,000 people asked to be evacuated, with some residents sitting on roofs waiting for help.

"The situation is alarming," said Mehmed Mustabasic, the mayor of Maglaj. "We have no electricity, the phones are not working. We are cut off from the rest of the world."

Bosnian military helicopters evacuated hundreds of people. The EU troops in Bosnia joined the effort with trucks and helicopters, but many roads remained stuck as snow blanketed higher elevations. Most schools were closed.

In Serbia, emergency officials said more than 600 people were evacuated, some by helicopter, and thousands were left without electricity and phone service. "We have engaged all our manpower," said Predrag Maric, a Serbian emergency official. "Water is rising everywhere."

Firefighters say a woman outside Belgrade drowned after she refused to be evacuated, and a firefighter died during a rescue operation in central Serbia. Serbian media said at least two more people were missing.