Civilians were also killed Sunday while trying to evacuate near a battered bridge in Irpin, a town outside the capital, Kyiv, visuals verified by The Washington Post showed.

More than 1.5 million refugees from Ukraine have fled to neighboring countries over the past 10 days, the U.N. high commissioner for refugees, Filippo Grandi, said Sunday. He tweeted that the mass exodus is xe2x80x9cthe fastest growing refugee crisis in Europe since World War II.xe2x80x9d Grandi recently predicted that more than 4 million people could be displayed by the conflict in the days to come.

Russian President Vladimir Putin said Sunday that Russia would press on with its invasion unless Ukraine stopped fighting.

It was time for Ukraine to xe2x80x9cshow a more constructive approach that fully takes into account the emerging realities,xe2x80x9d he said, according to the Kremlin, in an apparent reference to Ukrainexe2x80x99s military and territorial losses since Russiaxe2x80x99s invasion. Speaking by phone with Turkish President Recep Tayyip Erdogan, Putin said the war was xe2x80x9cgoing according to planxe2x80x9d and on time. He denied that Russia was responsible for the civilian casualty toll, according to a Russian readout of the call.

A spokesman for the Russian Defense Ministry said Sunday that the military had struck and disabled Ukrainexe2x80x99s Starokostiantyniv military air base, about 150 miles southwest of Kyiv, early Sunday, using long-range, high precision weapons. The airport was among dozens of targets, including a Russian-made air defense system owned by Ukraine, the spokesman said.

Later Sunday, in a video message, Ukrainian President Volodymyr Zelensky said that a missile strike on Vinnystia, about 70 miles southeast of the air base, had xe2x80x9ccompletely destroyed the airport.xe2x80x9d

Zelensky repeated his appeal for allied nations to impose a no-fly zone over Ukraine. xe2x80x9cWe repeat every day: Close the sky over Ukraine. Close it for all Russian rockets. For all Russian military aviation. For all these terrorists. Make a humanitarian airspace. Without rockets, without bombs from the air. We are people and this is your humanitarian obligation to protect us.xe2x80x9d

Failing that, supply xe2x80x9cairplanes so that we can protect ourselves,xe2x80x9d he added.

Secretary of State Antony Blinken said Sunday that the United States is exploring how it might supply Ukraine with fighter jets from NATO nations. xe2x80x9cWe are looking actively now at the question of airplanes that Poland may provide to Ukraine and looking at how we might be able to backfill should Poland choose to supply those planes,xe2x80x9d he told reporters during a visit to Chisinau, Moldova.

xe2x80x9cI canxe2x80x99t speak to the timeline but I can just tell you that wexe2x80x99re looking at it very, very actively,xe2x80x9d Blinken said.

Russia warned Sunday that foreign countries hosting Ukrainian combat aircraft could be viewed by Moscow as parties to the conflict.

xe2x80x9cWe know for a fact about Ukrainian combat planes which earlier flew to Romania and other neighboring countries,xe2x80x9d Russian Defense Ministry spokesperson Igor Konashenkov said Sunday. xe2x80x9cWe would like to point out that the use of the network of airfields of those countries for the stationing of Ukrainian combat aviation for the further use against the Russian Armed Forces could be viewed as the involvement of those countries in the armed conflict,xe2x80x9d he said.

In Irpin, outside Kyiv, video published Sunday showed a man wearing a yellow armband, usually worn by Ukrainian forces, and carrying a gun over his shoulder as he stands across from a church and sidewalk crowded with people carrying suitcases. He takes a few steps toward an intersection before an explosion rips through the middle of the street.

The area is covered in smoke. Someone runs out of the building and drags the man with the yellow armband out of the street. Soldiers sprint across the intersection to people collapsed on the ground, and someone shouts, xe2x80x9cMedic!xe2x80x9d

Associated Press photos of the aftermath show civilians killed in the attack. Lynsey Addario, a photographer working for the New York Times who witnessed the attack, said in a message posted on Twitter that xe2x80x9cat least three members of a family of four were killed in front of me.xe2x80x9d

Fahim reported from Istanbul, Cahlan from Washington and Ryan from Tallinn, Estonia. Jennifer Hassan in London and Danielle Paquette in Dakar, Senegal, contributed to this report.