Russian forces unleashed artillery fire on towns in eastern Ukraine, killing and wounding dozens of civilians, and began storming the bombed-out steel mill in Mariupol from where scores were evacuated after enduring weeks of shelling against the city’s last pocket of resistance.

The governor of the eastern Donetsk region said Russian attacks left 21 dead on Tuesday, the highest number of known fatalities since April 8, when a missile attack on the railway station in Kramatorsk killed at least 59 people.

Adding pressure on Moscow, the European Union’s leader on Wednesday called on the 27-nation bloc to ban Russian oil imports in a new wave of sanctions.

“We will make sure that we phase out Russian oil in an orderly fashion, in a way that allows us and our partners to secure alternative supply routes and minimizes the impact on global markets,” European Commission President Ursula von der Leyen told the European Parliament in Strasbourg, France. She also proposed that Sberbank, Russia’s largest bank, and two other major banks be disconnected from the SWIFT international banking payment system.

Thanks to the evacuation effort over the weekend, 101 people – including women, the elderly, and 17 children, the youngest 6 months old – emerged from the bunkers under Mariupol’s Azovstal steelworks to “see the daylight after two months,” said Osnat Lubrani, the U.N. humanitarian coordinator for Ukraine.

Ukraine’s Deputy Prime Minister Iryna Vereshchuk said authorities on Wednesday plan to continue efforts to evacuate civilians from Mariupol and nearby areas if the security situation allows it. Lubrani also expressed hope for further evacuations but said none had been worked out.

One evacuee said she went to sleep at the plant every night afraid she wouldn’t wake up.

“You can’t imagine how scary it is when you sit in the bomb shelter, in a damp and wet basement, and it is bouncing and shaking,” 54-year-old Elina Tsybulchenko said upon arriving in the Ukrainian-controlled city of Zaporizhzhia, about 140 miles (230 kilometers) northwest of Mariupol, in a convoy of buses and ambulances.

She said if the shelter were hit by a bomb like the ones that left the huge craters she saw on the two occasions she ventured outside, “all of us would be done.”

Evacuees, a few of whom were in tears, made their way from the buses into a tent offering food, diapers and connections to the outside world. Some of the evacuees browsed racks of donated clothing, including new underwear.

The news for those left behind was more grim. Ukrainian commanders said Russian forces backed by tanks began storming the sprawling plant, which includes a maze of tunnels and bunkers spread out over 11 square kilometers (4 square miles).

It was unclear how many Ukrainian fighters were still inside, but the Russians put the number at about 2,000 in recent weeks, and 500 were reported to be wounded. A few hundred civilians also remained there, Ukrainian Deputy Prime Minister Iryna Vereshchuk said.

“We’ll do everything that’s possible to repel the assault, but we’re calling for urgent measures to evacuate the civilians that remain inside the plant and to bring them out safely,” Sviatoslav Palamar, deputy commander of Ukraine’s Azov Regiment, said on the messaging app Telegram.

He added that throughout the night, the plant was hit with naval artillery fire and airstrikes. Two civilian women were killed and 10 civilians wounded, he said.

In his nightly video address, Ukrainian President Volodymyr Zelenskyy said that by storming the steel mill, Russian forces violated agreements for safe evacuations. He said the prior evacuations are “not a victory yet, but it’s already a result. I believe there’s still a chance to save other people.”

Among those killing in fresh attacks in Donetsk on Tuesday were 10 people at a chemical plant in the city of Avdiivka, Donetsk Gov. Pavlo Kyrylenko said.

“The Russians knew exactly where to aim – the workers just finished their shift and were waiting for a bus at a bus stop to take them home,” he wrote in a Telegram post. “Another cynical crime by Russians on our land.”

Another two civilians were killed and two wounded in overnight shelling in the neighboring Luhansk region, Gov. Serhiy Haidai said, adding Russian attacks were intensifying.

Just to the north, near the strategic junction city of Izyum, Russia has deployed 22 battalion tactical groups in its attempt to advance along the northern axis of the Donbas, the British Defense Ministry reported Wednesday. Each unit typically numbers about 800 soldiers.

Despite struggling to break through Ukrainian defenses and build momentum, Russia likely intends to proceed beyond Izyum to capture the cities of Kramatorsk and Severodonetsk, as they try to cut Ukrainian forces off in the region, according to the British assessment. However, Moscow’s push has been slow as Ukrainian fighters dig in and use long-range weapons, like howitzers, to target the Russians.

The U.S. believes Ukrainians in recent days have pushed Russian forces about 40 kilometers (25 miles) east of Kharkiv, which lies outside the Donbas but is key to the offensive there. Extending the distance of the front line makes it more difficult for Russia to target the city with artillery fire.

Ukraine’s eastern industrial heartland of Donbas, which includes Donetsk and Luhansk, remains Moscow’s stated objective after failing to take Kyiv in the early weeks of the war.

Explosions were also heard in Lviv, in western Ukraine, near the Polish border. The strikes damaged three power substations, knocking out electricity in parts of the city and disrupting the water supply, and wounded two people, the mayor said. Lviv has been a gateway for NATO-supplied weapons and a haven for those fleeing the fighting in the east.

Russian Defense Ministry spokesman Maj. Gen. Igor Konashenkov said Russian aircraft and artillery hit hundreds of targets in the past day, including troop strongholds, command posts, artillery positions, fuel and ammunition depots and radar equipment.

Ukrainian authorities said the Russians also attacked at least a half-dozen railroad stations around the country.

The assault on the Azovstal steelworks began almost two weeks after Russian President Vladimir Putin ordered his military not to storm the plant to finish off the defenders but to block it off. The first – and so far only – civilians to be evacuated from the shattered plant got out during a brief cease-fire in an operation overseen by the U.N. and the Red Cross.

“I’m very glad to be on Ukrainian soil,” said a woman who gave only her first name, Anna, and arrived with two children, ages 1 and 9. “We thought we wouldn’t get out of there, frankly speaking.”

In addition to the 101 people evacuated from the steelworks, 58 joined the convoy in a town on the outskirts of Mariupol, Lubrani said. About 30 people who left the plant decided to stay behind in Mariupol to try to find out whether their loved ones were alive, Lubrani said. A total of 127 evacuees arrived in Zaporizhzhia, she said.

The Russian military said earlier that some of the evacuees chose to stay in areas held by pro-Moscow separatists.

Mariupol has come to symbolize the human misery inflicted by the war. The Russians’ two-month siege of the strategic southern port has trapped civilians with little or no food, water, medicine or heat, as Moscow’s forces pounded the city into rubble. The plant in particular has transfixed the outside world.

Mariupol’s fall would deprive Ukraine of a vital port, allow Russia to establish a land corridor to the Crimean Peninsula, which it seized from Ukraine in 2014, and free up troops for fighting elsewhere in the Donbas.