KYIV, Ukraine — Ukraine struck the headquarters of Russia’s Black Sea Fleet in a missile attack Friday that left a serviceman missing and the main building smoldering, according to military officials on both sides of the war and images from the scene in Crimea.

The Russian Defense Ministry initially said one service member was killed but then issued a statement saying he was missing following the attack at the port city of Sevastopol.

The Crimean Peninsula, which Russia illegally annexed from Ukraine in 2014, has been a frequent target since President Putin ordered a full-scale invasion of Ukraine almost 19 months ago.

Crimea has served as the key hub supporting Moscow’s invasion of Ukraine. The main base of Russia’s Black Sea Fleet since the 19th century, Sevastopol, has had a particular importance for navy operations since the start of the invasion of Ukraine.

Ukraine has increasingly targeted naval facilities in Crimea in recent weeks while the brunt of its summer counteroffensive makes slow gains in the east and south of Ukraine, the Institute for the Study of War said Thursday.

Military experts say it is essential for Ukraine to keep up its attacks on targets in Crimea to degrade Russian morale and weaken its military.

The attack came a day after Russia pounded cities across Ukraine with missiles and artillery strikes, killing at least five people as President Zelensky met with President Biden and congressional leaders at Washington while a $24 billion aid package is under consideration. Mr. Zelensky was in Canada on Friday to address its Parliament in his ongoing effort to bolster support from Western allies.

Previous attacks in Crimea resulted in several civilian deaths, but Russian officials haven’t yet reported any military personnel killed. Six people were reported wounded following a July 2022 attack on the fleet’s headquarters, but it wasn’t clear whether they were civilians or servicemembers.

The Russian-installed governor of Sevastopol, Mikhail Razvozhayev, said no one was injured Friday outside of the burning headquarters building.

The Ukrainian military claimed responsibility for the attack.

“We promised that ‘there will be more,'” the air force commander, Lieutenant General Mykola Oleschuk, said in a social media post that thanked pilots and showed video of air sirens blazing and smoke rising from the building.

The Russian Defense Ministry said five missiles were shot down by Russian air defense systems responding to the attack on Sevastopol. It was not immediately clear if the headquarters was hit in a direct strike or by debris from an intercepted missile.

Sevastopol residents said they heard explosions and saw smoke, Russian news outlets reported, and images showed gray plumes over the seafront. The Associated Press could not immediately verify the videos.

A stream of ambulances arrived at the fleet’s headquarters, and shrapnel was scattered hundreds of yards around, Russian state news agency Tass reported.

One official with the Crimean administration, Oleg Kryuchkov, said a cruise missile downed near Bakhchysarai, about 18.5 miles inland, sparked a grass fire.

Mr. Razvozhayev said civilian infrastructure wasn’t damaged but did not mention the impact on the fleet headquarters.

He urged Sevastopol residents not to go to the central part of the city, saying roads were closed and unspecified “special efforts” were underway. Police asked residents to leave the central part of the city, Tass said.

The attack Friday is one of several recently launched by Ukraine in the Crimea area.

The Institute for the Study of War said satellite imagery this week showed that Ukrainian strikes had significantly damaged a communications command center at Verkhnosadove, just outside Sevastopol.

Russian-installed authorities at Sevastopol accused Ukraine on September 13 of carrying out the biggest attack in Crimea in weeks, one on a strategic shipyard that damaged two ships undergoing repairs and caused a fire at the facility.

Two days earlier, Ukraine claimed it had recaptured strategic gas and oil drilling platforms in the Black Sea that Russia seized in 2015. Russia had used the platforms for electronic warfare equipment and to launch helicopters, and Ukraine said getting control of them would help it regain Crimea.