Russia demanded that Ukrainians in the besieged city of Mariupol lay down their arms Monday in exchange for safe passage out of town, but Ukraine rejected the offer.

The Russian demand came hours after it bombed an art school that was sheltering about 400 people, according to Ukrainian authorities.

Russian Col. Gen. Mikhail Mizintsev said it would allow two corridors out of the coastal city, heading either east toward Russia or west to other parts of Ukraine.

Mariupol residents were given until 5 a.m. Monday to respond to the offer, which included them raising white flags. Russia didn’t say what action it would take if the offer was rejected.

But Ukrainian Deputy Prime Minister Irina Vereshchuk said no.

“There can be no talk of any surrender, laying down of arms. We have already informed the Russian side about this,” she told the news outlet Ukrainian Pravda. “I wrote: `Instead of wasting time on eight pages of letters, just open the corridor.’”

Mariupol Mayor Piotr Andryushchenko also rejected the offer, saying in a Facebook post he didn’t need to wait until morning to respond and cursing at the Russians, according to the news agency Interfax Ukraine.

The Russian Ministry of Defense also said authorities in Mariupol could face a military tribunal if they sided with what it described as “bandits,” the Russian state news agency RIA Novosti reported.

Previous bids to allow residents to evacuate Mariupol and other Ukrainian cities have failed or have been only partially successful, with bombardments continuing as civilians sought to flee.

Earlier Sunday, Ukrainian authorities said Russia’s military bombed an art school in Mariupol, and tearful evacuees from the devastated port city described how “battles took place over every street,” weeks into the siege.

Speaking in a video address early Monday, Ukraine’s President Volodymyr Zelenskyy said that about 400 civilians were taking shelter at the art school in the besieged Azov Sea port city when it was struck by a Russian bomb.