KYIV — President Zelensky fired the commander of the country’s air force Friday, four days after an F-16 warplane that Ukraine received from its Western partners crashed during a Russian bombardment and killed the pilot.

The order to dismiss Lieutenant General Mykola Oleshchuk was published on the presidential website.

“We need to protect people. Protect personnel. Take care of all our soldiers,” Mr. Zelensky said in an address minutes after the order was published. He said Ukraine needs to strengthen its army on the command level.

Lieutenant General Anatolii Kryvonozhko was appointed acting air force commander, the army’s general staff said.

The dismissal came on the same day that General Oleshchuk directed scathing criticism at a lawmaker who is deputy head of the Ukrainian parliament’s defense committee for her claims that the F-16 was downed by a Patriot air-defense system. Ukraine has received an unspecified number of the American-made systems.

The member of parliament, Mariana Bezuhla, cited unnamed sources for her claim and demanded punishment for those responsible for the error.

General Oleshchuk accused Ms. Bezuhla of defaming the air force and discrediting American arms manufacturers and said that he hoped she would face legal consequences for her claims.

“The truth will win,” Ms. Bezuhla posted on X shortly after the dismissal order was published.

The air force did not directly deny that the F-16 was hit by a Patriot missile.

American analysts have joined the Ukrainian investigation into the crash, the air force said.

Meanwhile, a Russian attack on the northeastern city of Kharkiv using powerful plane-launched glide bombs killed six people, including a 14-year-old girl on a playground, and wounded 47 others, the regional governor, Oleh Syniehubov, said.

The bombs struck five locations across the city, which had a prewar population of 1.4 million people, the governor said.

One of the bombs hit a 12-story apartment block, setting the building ablaze and trapping at least one person on an upper floor. Emergency crews searching for survivors feared the structure could collapse.

Mr. Zelensky pointed to the Kharkiv strikes as further evidence that Western partners should scrap restrictions on what the Ukrainian military can target with donated weapons.

The Kharkiv strike “wouldn’t have happened if our defense forces had the capability to destroy Russian military aviation at its bases. We need strong decisions from our partners to stop this terror,” Mr. Zelensky said.

F-16s are one of the weapons that could be used to hit Russian bases behind the front line.

General Oleshchuk said on Telegram that “a detailed analysis” was already being conducted into why the F-16 jet went down Monday, when Russia launched a major missile and drone barrage at Ukraine.

“We must carefully understand what happened, what the circumstances are, and whose responsibility it is,” General Oleshchuk wrote in the post shortly before his dismissal.

The crash was the first reported loss of an F-16 in Ukraine, where the warplanes arrived at the end of last month. At least six are believed to have been delivered by European countries.

Military analysts say the planes will not be a game-changer in the war, given Russia’s huge air force and sophisticated air-defense systems. Ukrainian officials welcomed the supersonic jets, though. They can carry modern weapons used by NATO countries, offering an opportunity for Kyiv to hit back at Russia’s air superiority.

On the ground, the Russian army is making slow but gradual progress in its drive into eastern Ukraine, while Ukrainian forces are holding ground in the Kursk border region of western Russia after a recent incursion.

The Institute for the Study of War said it expected that Ukraine would lose some Western-provided military equipment in the fighting.

The Washington-based think tank added, though, that “any loss among Ukraine’s already limited allotment” of F-16s and trained pilots “will have an outsized impact” on the country’s ability to operate F-16s “as part of its combined air defense umbrella or in an air-to-ground support role.”