The main structure of the plant has been largely destroyed, NDTV reported, citing officials who said the casualty figures could change.

The facility, located in Sumy, had continued operations despite the ongoing war between Russia and Ukraine. However, the latest drone strike caused extensive damage to the plant.

The losses are estimated to be at least Rs 400 crore, according to NDTV.

According to the company's official website, Kusum Group was established in 1996 and has grown from a local business into one of Ukraine's leading pharmaceutical companies. The group is reportedly run by Indian national Rajeev Gupta.

Meanwhile, Ukrainian President Volodymyr Zelenskyy condemned the latest Russian strikes, saying drones had targeted multiple locations across the country.

"This morning, the Russians once again struck the Pivnichnyi Bridge in Kyiv with a drone. They attacked an ordinary pharmaceutical warehouse in Sumy with drones. Tragically, one person was killed. My condolences to the family and loved ones. In Dnipro, they struck a communications facility. Six people were injured as a result of these attacks," Zelenskyy wrote on X.

He said Russia had launched 135 drones against Ukraine overnight, with Kyiv, Dnipro, Kharkiv, Donetsk, Sumy and Zaporizhzhia among the regions targeted.

"Among the main targets of these terrorists, as always, are ordinary residential buildings, critical infrastructure — everything that makes up normal everyday life," Zelenskyy said, adding that some communities were experiencing power outages and emergency services were working at the affected sites.

The Ukrainian president also called for continued international support, warning that Russian attacks had intensified.

"It is important that Ukraine is not left alone against this terror," he said.

Zelenskyy added that Russia had deployed more than 1,900 attack drones, 1,700 aerial bombs and 25 missiles against Ukraine in the past week. More than 800 of the drones were jet-powered, he said, calling for Russia to be held accountable for the escalation.

The latest attacks came as German Chancellor Friedrich Merz made a surprise visit to Kyiv on Sunday, signalling Berlin's continued support for Ukraine.

Welcoming Merz, Zelenskyy said Germany had consistently demonstrated leadership in helping protect Ukrainian lives from Russian attacks. He added that the two countries were preparing agreements aimed at strengthening the defence capabilities of Ukraine and Europe.

"Russia must be stopped together. Thank you to everyone who is helping," Zelenskyy wrote on X.

Merz, meanwhile, shared a photograph of his meeting with Zelenskyy and reaffirmed Germany's commitment to supporting Ukraine.

"Ukraine is facing decisive weeks. That is why I travelled to Kyiv today with the message: You can rely on us," Merz said.

He added that Germany's own security depended on the outcome of the war and described Berlin's support for Kyiv as being in Germany's own strategic interest.