KYIV — Thousands of residents from the northeastern Ukrainian city of Sumy were successfully evacuated after Russia agreed to pause attacks and evacuation corridors opened.

Evacuations began on Tuesday morning, with buses heading towards the city of Poltava, further south and away from the front lines.

About 5,000 people and more than 1,000 private vehicles "are already in safety", said Kyrylo Tymoshenko, deputy head of President Volodymyr Zelensky's office.

It was the first successful mass evacuation despite Russia announcing several ceasefires to get people out of cities under bombardment.

A similar attempt for people trapped in Chernihiv failed because Russia kept shelling the exit route, Ukraine claimed.

Sumy's regional governor said the humanitarian corridor would continue working on Wednesday.

The United Nations estimates that more than 2 million people have fled Ukraine since Moscow's invasion on February 24.

The governor of the north-eastern city of Ukraine says a humanitarian corridor that was opened earlier on Tuesday, is set to continue on Wednesday.

Some 5,000 people were estimated to have left Sumy in two evacuation stages, according to the Ukrainian government.

Sumy, near the Russian border, has for days been under fierce Russian bombardment.

On Monday alone, 22 people - including three children - were killed in Russian air strikes, local officials said.

Moscow has announced another humanitarian ceasefire to allow civilians in cities under attack to flee, according to reports by Russian state media outlets.

The corridors will again be set up for Kyiv, Chernihev, Sumy, Kharkiv and Mariupol at 10:00 local time [07:00 GMT]. It's the third time a ceasefire - most of which have failed - has been announced by Moscow. — BBC