In the Ukrainian port city of Mykolaiv, residential areas are increasingly under threat.

Residential areas of Ukraine’s Black Sea port of Mykolaiv have been under near constant bombardment for days, according to local officials, the latest escalation in a southern city as Russian forces have increasingly shifted focus to the region and the east of the country.

Last week, a missile blasted a hole in the side of a government building in Mykolaiv, killing dozens. On Sunday, deadly strikes injured a 15-year-old, among several others. On Monday, at least 11 people were killed and 61 wounded in attacks, the regional governor said.

Shelling in the city has continued nearly every day for weeks, but civilian infrastructure and homes have increasingly been targeted, local officials and soldiers say. Russian forces have struck residential buildings, a hospital, an orphanage and schools in recent days, Oleksandr Senkevych, the mayor of Mykolaiv, said.

The assault on the city and others in Ukraine’s south comes as Russian forces refocus after withdrawing from positions in the north and northeast. Mykolaiv is a main target because of its location along the Black Sea coast between Russian forces in the east and Odesa, the headquarters of the Ukrainian Navy and the country’s largest civilian port, in the west.

Russian forces have increasingly laid siege to cities they have failed to control, targeting civilians and infrastructure to demoralize populations. In the case of places like Mariupol, the besieged southern port city, they have used hunger as a weapon of war, military analysts say.

Ukrainian soldiers defending Mykolaiv said most of the attacks in recent days appeared to be directed at civilian targets rather than at their positions in and around the city.

“Two days ago, some bombs hit our positions, but now it’s quiet,” said Sgt. Ruslan Khoda, who is based in Mykolaiv.

On Tuesday and Wednesday, air raid alarms again echoed through the early morning hours in Mykolaiv, according to Mr. Senkevych, who urged residents to take shelter immediately in a series of posts on social media.

The Russian government has said it is targeting military infrastructure. On Tuesday, the Russian Defense Ministry said in a statement that air-based and land-based missiles had destroyed five Ukrainian fuel depots, including in Mykolaiv, which it said were being used to resupply Ukrainian forces in the area.

Military analysts have said the actions in the region are part of Russia’s broader offensive. Jens Stoltenberg, the secretary general of NATO, said in a news conference ahead of a meeting with foreign ministers on Wednesday and Thursday that in coming weeks a further Russian push is expected in eastern and southern Ukraine.

The goal, he said, is to take the entire Donbas region in Ukraine’s east, portions of which have been held by Russia-backed separatists since 2014, and to create a land bridge to Crimea, which was annexed by Russia in 2014.

Vitaly Kim, the governor of the Mykolaiv region, said that missiles struck a children’s hospital on Monday. He shared video of the attack in which a British ambulance that had been donated to the hospital was hit. The video could not immediately be verified.

Mr. Kim, in a separate video message posted early on Wednesday to his Telegram channel, said that the situation overnight had remained relatively calm and that he had talked with residents of the city and the region.

“People are tough,” he said, but added that “after the atrocities in Bucha, the mood is completely different and direct clashes will be different.”

Troops based in the region said they have learned the rhythms of Russian attacks and know how to protect themselves, limiting casualties among soldiers.

“We are well dug in and have learned how to act during shelling,” said a sergeant from the Mykolaiv-based 79th Air Assault Brigade, who would only give his first name, Andrei. “I feel sorry for the civilian population, who should not be dying.”