ZAPORIZHZHIA, Ukraine (AP) — Russia pounded away at Ukraine’s vital southern port of Odesa, Ukrainian officials said Tuesday, they announced they found the bodies of 44 civilians in the rubble of a building in the northeast that was destroyed weeks ago.

Meanwhile, a Ukrainian official said that at least 100 civilians remain trapped at a steel mill in the besieged city of Mariupol, where Ukrainian fighters are making a last stand.

The 44 bodies were found in a five-story building that collapsed in March in Izyum, about 120 kilometers (75 miles) from the city of Kharkiv, which has been under sustained Russian attack since the beginning of the war in late February.

“This is another horrible war crime of the Russian occupiers against the civilian population!” said Oleh Synehubov, the head of the regional administration, in a social media message announcing the deaths.

Izyum lies on a key route to the eastern industrial region of the Donbas, now the focus of Russia's war in Ukraine. Synehubov did not say specifically where the building was.

Earlier, the Ukrainian military said Russian forces fired seven missiles a day earlier from the air at the crucial Black Sea port of Odesa, hitting a shopping center and a warehouse. One person was killed and five were wounded, the military said.

Ukraine alleged at least some of the munitions used dated back to the Soviet era, making them unreliable in targeting. Ukrainian, British and American officials warn Russia is rapidly expending its stock of precision weapons and may not be able to quickly build more, raising the risk of more imprecise rockets being used as the conflict grinds on. That could result in wider damage and more civilian deaths.

But the Center for Defense Strategies, a Ukrainian think tank tracking the war, said Moscow did use some precision weapons against Odesa: Kinzhal, or “Dagger,” hypersonic air-to-surface missiles.

Using advanced guided missiles allows Russia to fire at a distance without being exposed to potential anti-aircraft fire.

The strikes came the same day Russian President Vladimir Putin marked his country’s biggest patriotic holiday without being able to boast of major new battlefield successes. On Monday, he watched troops march in formation and military hardware roll by in a Victory Day parade on Moscow’s Red Square to celebrate the Soviet Union’s role in the 1945 defeat of Nazi Germany.

Many Western analysts had expected Putin to use Victory Day holiday to trumpet some kind of victory in Ukraine or announce an escalation, but he did neither. Instead, he sought to justify the war again as a necessary response to what he portrayed as a hostile Ukraine.

Putin has long bristled at NATO’s creep eastward into former Soviet republics. Ukraine and its Western allies have denied the country posed any threat.

“The danger was rising by the day,” Putin said. “Russia has given a preemptive response to aggression. It was forced, timely, and the only correct decision.”

Intense fighting also raged in Ukraine’s east, including at a steel plant in Mariupol, where Russian forces sought to take the last pocket of Ukrainian resistance.

One of the Ukrainian fighters holding out at the steel plant said they were still defending the city. Valeri Paditel, who heads the border guards in the Donetsk region, said the fighters were “doing everything to make those who defend the city in the future proud.”

Hundreds of civilians holed up for weeks with the fighters have been evacuated in recent days. But Petro Andryushchenko, an advisor to the Mariupol mayor, said in a social media post Tuesday that “in addition to the military, at least 100 civilians remain” at the sprawling plant, which has miles of underground tunnels. At one point, Ukrainian and Russian authorities had said all civilians had left the plant.

Andryushchenko said that the Russian forces continue to pound the plant with heavy weaponry and “attempts to storm (the plant) from the land remain unsuccessful.”

The Ukrainian military warned Tuesday that Russia could target the country’s chemical industries. The claim wasn’t immediately explained in the report. But Russian shelling has previously targeted oil depots and other industrial sites during the war.

Also, satellite pictures analyzed by The Associated Press showed two ships off Ukraine’s Snake Island on Monday afternoon.

One of the ships seen in the images from Planet Labs PBC appeared to be a landing craft. Ukraine has repeatedly struck Russian positions there recently, suggesting Russian forces may be trying to re-staff or remove personnel from the Black Sea island.

After unexpectedly fierce resistance forced the Kremlin to abandon its effort to storm Kyiv in the early days of the war, Moscow's forces have concentrated on capturing the Donbas.

But the fighting there has been a back-and-forth, village-by-village slog. Some analysts suggested Putin might declare the fighting a war, not just a “special military operation,” and order a nationwide mobilization, with a call-up of reserves, to fight an extended conflict.

In the end, he gave no signal as to where the war is headed or how he might intend to salvage it. Specifically, he left unanswered the question of whether or how Russia will marshal more forces for a continuing war.

“Without concrete steps to build a new force, Russia can’t fight a long war, and the clock starts ticking on the failure of their army in Ukraine,” tweeted Phillips P. O’Brien, professor of strategic studies at the University of St. Andrews in Scotland.

Nigel Gould Davies, former British ambassador to Belarus, said: “Russia has not won this war. It’s starting to lose it.”

He said that unless Russia has a major breakthrough, “the balance of advantages will shift steadily in favor of Ukraine, especially as Ukraine gets access to growing volumes of increasingly sophisticated Western military equipment.”

As Putin laid a wreath in Moscow, air raid sirens echoed again in the Ukrainian capital. But Ukrainian President Volodymyr Zelenskyy declared in his own Victory Day address that his country would eventually defeat the Russians.

“Very soon there will be two Victory Days in Ukraine,” he said in a video. He added: "We are fighting for freedom, for our children, and therefore we will win.”

A Zelenskyy adviser interpreted Putin’s speech as indicating that Russia has no interest in escalating the war through the use of nuclear weapons or direct engagement with NATO.

In Washington, President Joe Biden signed a bipartisan measure to reboot the World War II-era “lend-lease” program, which helped defeat Nazi Germany, to bolster Kyiv and Eastern European allies.

Russia has about 97 battalion tactical groups in Ukraine, largely in the east and the south, a slight increase over last week, according to a senior U.S. official, speaking on condition of anonymity to discuss the Pentagon's assessment. Each unit has roughly 1,000 troops, according to the Pentagon.

The official said that overall, the Russian effort in the Donbas hasn’t achieved any significant progress in recent days and continues to face stiff resistance from Ukrainian forces.

Satellite photos showed intense fires in Russian-held territory in southern Ukraine on Monday. A cause for the fires wasn’t immediately clear. However, Planet Labs images showed thick smoke rising to the east of Vasylivka, a city which is flanked by nature preserves.

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Gambrell reported from Lviv, Ukraine. Yesica Fisch in Bakhmut, David Keyton in Kyiv, Yuras Karmanau in Lviv, Mstyslav Chernov in Kharkiv, Lolita C. Baldor in Washington, and AP staff around the world contributed to this report.