KHERSON, Ukraine (AP) — Ukrainian President Volodymyr Zelenskyy hailed the Russian withdrawal from Kherson as the “beginning of the end of the war” on Monday, as he lauded soldiers and took selfies with them in the recently liberated southern city.

The retaking of Kherson after a grinding offensive that forced Russia to pull back its forces from the city was one of Ukraine’s biggest success so far of the nearly nine-month invasion and a stinging blow to the Kremlin.

Zelenskyy walked the streets of the city Monday, just hours after warning in his nightly video address of booby traps and mines left behind in the city by the Russians before their retreat.

Zelenskyy has previously appeared unexpectedly in other front-line zones at crucial junctures of the war, to support troops and congratulate them for battlefield exploits.

In Kherson, he distributed medals to soldiers Ukrainian troops in a central square and posed for selfies with them.

Video footage also showed him waving to residents who waved at him from an apartment window and yelled “Glory to Ukraine!” The reply “Glory to the heroes!” came back from Zelenskyy’s group, made up of soldiers and others.

Kremlin spokesman Dmitry Peskov on Monday refused to comment on Zelenskyy’s visit to Kherson, saying only that, “You know that it is the territory of the Russian Federation.”

The liberation of Kherson after a grinding offensive that forced Russian to withdraw its forces from the city was one of Ukraine’s biggest success so far of the nearly nine-month invasion and a stinging blow for the Kremlin.

After the Russian retreat, Ukrainian authorities say they are finding evidence of torture and other atrocities.

In his nightly video address on Sunday, Zelenskyy said without details that “investigators have already documented more than 400 Russian war crimes, and the bodies of both civilians and military personnel have been found.”

“In the Kherson region, the Russian army left behind the same atrocities as in other regions of our country,” he said. “We will find and bring to justice every murderer. Without a doubt.”

The end of Russia’s eight-month occupation of Kherson city has sparked days of celebration, but also exposed a humanitarian emergency, with residents living without power and water and short of food and medicines. Russia still controls about 70% of the wider Kherson region.

Zelenskyy said Russian soldiers who were left behind when their military commanders abandoned the city last week are being detained. He also spoke, again without details, of the “neutralization of saboteurs.”

Ukrainian police have called on residents to help identify people who collaborated with Russian forces.

Zelenskyy urged people in the liberated zone to also be alert for booby traps, saying: “Please, do not forget that the situation in the Kherson region is still very dangerous. First of all, there are mines. Unfortunately, one of our sappers was killed, and four others were injured while clearing mines.”

And he promised that essential services would be restored.

“We are doing everything to restore normal technical capabilities for electricity and water supply as soon as possible,” he said. “We will bring back transport and post. Let’s bring back an ambulance and normal medicine. Of course, the restoration of the work of authorities, the police, and some private companies are already beginning.”

Residents said departing Russian troops plundered the city, carting away loot as they withdrew last week. They also wrecked key infrastructure before retreating across the wide Dnieper River to its east bank.

One Ukrainian official described the situation in Kherson as “a humanitarian catastrophe.”

Reconnecting the electricity supply is the priority, with gas supplies already assured, Kherson regional governor Yaroslav Yanushevych said.

The Russian pullout marked a triumphant milestone in Ukraine’s pushback against Moscow’s invasion almost nine months ago. In the past two months, Ukraine’s military claimed to have retaken dozens of towns and villages north of the city of Kherson.

Ukraine’s liberation of Kherson was the latest in a series of battlefield embarrassments for the Kremlin. It came some six weeks after Russian President Vladimir Putin annexed the Kherson region and three other provinces in southern and eastern Ukraine — in breach of international law — and declared them Russian territory.