KYIV, Ukraine (AP) — Russia and Ukraine exchanged strikes overnight that killed civilians and injured many others on both sides, local authorities reported.

Large-scale Russian missile strikes on Ukrainian cities have become almost routine in recent weeks, with Moscow exploiting Ukraine's critical shortage of interceptors for the U.S.-made Patriot systems — the sole air defense weapon in its arsenal able to shoot down ballistic missiles.

In the latest attacks, Ukrainian drones killed five people and injured two dozen others, including a 4-year-old boy, in Russia's border region of Belgorod, according to the regional administration.

In Kharkiv, Ukraine's second-largest city, Russian missiles struck a high-rise apartment block in the Saltivskyi district, killing two people and injuring 13, according to regional head Oleh Syniehubov. Eight more people were injured in Ukraine's Black Sea port of Odesa after "dozens of missiles and drones" struck the city and surrounding region, according to local administration head Oleh Kiper.

Ukraine's President Volodymyr Zelenskyy has for months lobbied other countries, especially the U.S., to send Ukraine more Patriot systems made scarcer by the Iran war, arguing they are crucial for defending civilians.

Failing that, Zelenskyy wants to make Patriot ammunition in Ukraine or get approval from Elon Musk to use his Starlink satellite communications system to guide strikes inside Russia that can hit its missile launchers.

Meanwhile, Kyiv has kept up long-range drone strikes against Russian energy infrastructure, as well as the country's largest online retailer, Wildberries, and other targets deep inside Russia, sparking a fuel crisis.

Russia's defense ministry on Sunday claimed its overnight strikes hit drone warehouses in the Kharkiv region, as well as fuel depots and stores of other materiel belonging to Ukraine's armed forces at the port of Odesa.

It said its forces had shot down 153 Ukrainian drones during the night, including over Russian-occupied Crimea and the Black and Azov seas.

In Russia's Belgorod region, authorities said Ukrainian drone strikes damaged 29 apartment blocks and five private houses, as well as administrative buildings and unspecified "commercial facilities."

Debris from Ukrainian drones also fell on two enterprises and a private home in the Russian city of Novorossiysk, mayor Andrey Kravchenko said on Sunday. He did not specify what the commercial sites were. Regional authorities later said falling debris had injured one person, damaged two private houses, and blew out a window in an apartment block.

A major fuel terminal is located at Novorossiysk that links Kazakhstan's oil fields to markets around the world, and which has previously been a target for Ukrainian strikes.

Elsewhere, Bulgaria has summoned Ukraine's ambassador after a drone entered Bulgarian airspace, the country's public broadcaster BNT reported on Sunday.

The drone exploded on Saturday close to an international gas pipeline shortly after crossing the border from Romania. No casualties or damage were reported.

Bulgaria's defense ministry said the drone appeared to be the type used by Ukrainian armed forces, and that the incident was likely accidental.

Ukrainian Foreign Ministry spokesman Heorhii Tykhyi said the incident was being examined but that it did not deliberately target Bulgaria. Ukraine and Bulgaria were in "close contact" to clarify what had happened, he added.