A part of a ten-storey apartment building in the southwestern Russian city of Belgorod collapsed after being hit by fragments of a downed Ukrainian missile, killing at least eight people and wounding about 20.

Casualty figures are expected to rise as more people are believed to have been trapped under the rubble.

Below are key facts about the incident, known at this point.

Circumstances of the incident

- The armed forces of Ukraine have been shelling the borderline city of Belgorod and its outskirts heavily throughout the day. Civil defense sirens in the area sounded at least eight times on Sunday.

- Ukrainian forces, presumably based in the Kharkov Region settlement of Kazachya Lopan not far from the border with Russia, shelled residential districts of Belgorod at around 11:40 a.m. Moscow time (8:40 a.m. GMT).

- Tochka-U missiles, Olkha multiple rocket launchers and Czech-made RM-70 Vampire systems were used during the attack. Russian air defenses repelled the assault, but fragments of a downed Tochka-U missile crashed into an apartment building.

Aftermath of the attack

- The impact caused an entire stairwell of a ten-storey residential building in the southwestern part of Belgorod to collapse.

- Fragments hit the building somewhere around its third floor, causing extensive damage to the entire structure. At least 40 apartments collapsed completely. Another 62 apartments in three buildings were damaged.

- At least eight people were reported to have been killed and 20 - wounded, including two children. Six victims are receiving out-patient treatment, the rest were hospitalized.

- More people are thought to have been trapped under the rubble. At least seven people remain unaccounted for, including an entire family with a child.

Rescue effort

- The rescue effort continues, although the damaged building is highly unstable and therefore unsafe. As the rescue and recovery mission proceeded on Sunday afternoon, several people were trapped by falling fragments of the roof. Three rescuers were injured and later diagnosed with fractures.

- Besides, the rescue operation had to be paused several times due to continuous Ukrainian rocket and missile attacks. Several explosions were heard in Belgorod when Kiev troops attacked the city for the seventh time on Sunday.

- Governor Vyacheslav Gladkov arrived on the site of the tragedy. He is helping rescuers to clear the rubble.

- Temporary shelters were set up to accommodate the affected residents, including those living in apartments adjacent to the collapsed stairwell.

- Rescue teams from the Russian emergencies ministry are preparing to leave for Belgorod. The ministry’s rescue center, based in the Central Russian city of Tula, is also ready to send its specialists to the city should the need arise.

Government’s response

- Russian President Vladimir Putin has heard reports delivered by acting emergencies minister Alexander Kurenkov and Governor Vyacheslav Gladkov, and gave all the necessary instructions, Kremlin spokesman Dmitry Peskov said. The presidential press secretary described the Ukrainian attack as "barbaric."

- Local self-defense units have been put on high alert. Bomb squads of the Russian National Guard have been dispatched to the area. Regional authorities assure that they have enough rescue and police personnel to cope with the current emergency on their own.

- The region’s ministry of construction is now assessing damage sustained by the building. Russian Acting Construction Minister Irek Faizullin pledged various support to those affected.

- Russia’s Acting Health Minister Mikhail Murashko ordered to dispatch a team of doctors to the city. A total of ten ambulance teams are already on their way from Moscow.

- The Russian Investigative Committee launched a criminal case on charges of a terror attack.

- The Russian military has identified the presumed location from where the missile was fired and is taking measures to suppress enemy fire.

- Russian regions of Lipetsk, Irkutsk, Moscow and Crimea, as well as the mayors of Moscow and Kursk, have offered assistance to the administration of Belgorod.

- The Russian presidential commissioner for children’s rights, Maria Lvova-Belova, is following the situation.

Waiting for international response

- The Russian Foreign Ministry’s official spokeswoman, Maria Zakharova, blamed the attack on the Kiev government and its western sponsors.

- Rodion Miroshnik, the Russian Foreign Ministry’s ambassador-at-large in charge of overseeing the Kiev regime’s crimes, described the attack as a clear violation of the international humanitarian law. He pledged to hold Kiev responsible for its atrocities.

- Russian Human Rights Commissioner Tatyana Moskalkova called upon the global community to condemn the Kiev government’s attacks on civilians.

- The Russian permanent mission to the Organization for Security and Cooperation in Europe (OSCE) urged the international community to strongly condemn this act of terror, emphasizing that Kiev used NATO weaponry during the attack.

- The office of the UN secretary-general issued a statement, condemning all attacks on civilian facilities.