Ukrainian officials warn death toll could rise after attack on a residential area on the city in southeast Ukraine.

A rescue operation was under way, Ukrainian President Volodymyr said on Wednesday, without providing additional information about the attack.

Regional governor Yuriy Malashko initially said three people died in the attack on a residential area, but Interior Minister Ihor Klymenko later said two people died and one other person had been resuscitated.

A video posted by Zelenskyy showed smoke billowing from burning and badly damaged buildings next to a church.

Zaporizhzhia, an important city on the Dnipro River, lies some 44 kilometres (27 miles) from the front line.

The number of victims could rise in the attack, which damaged a residential area, Malashko said on Telegram.

Earlier, Zaporizhzhia city council’s secretary, Anatoliy Kurtev, said that Russia had hit a residential area of the city.

The city lies about 50km (30 miles) northeast of the Zaporizhzhia Nuclear Power Plant, which has been occupied by Russian forces since the early weeks of the war. Shelling in the plant’s surroundings has raised persistent fears of a nuclear accident.

Meanwhile in Russia, an explosion on the grounds of a factory that makes optical equipment for Russia’s security forces north of Moscow killed one person, wounded 60 others and left at least eight people unaccounted for, officials said.

Wednesday’s blast occurred in the Russian town of Sergiyev Posad, some 50km (30 miles) northeast of Moscow, local authorities said.

Andrei Vorobyov, governor of the Moscow region, said the premises had been rented by a private firm, and that a criminal investigation had been opened into possible violations of safety procedures.

He said 38 apartment blocks in the surrounding area had been damaged, along with two schools, a sports complex and a store.

Russia’s TASS news agency quoted emergency services as dismissing early reports that the blast could have been caused by a drone attack, many of which have taken place in Moscow and the surrounding area in recent weeks and months, attributed by Russia to Ukraine.

Footage posted on social media showed a huge column of smoke rising above the town.

TASS reported that a major rescue operation involving more than 150 people was under way, citing the Emergencies Ministry as saying it had sent its lead units, “Tsentrospas” and “Leader”, to the site of the blast.

Russian agencies quoted local authorities as saying a state of emergency had been declared in the area.