Police discovered posts about his “dissatisfaction with the system in Ukraine.”

Local Ukrainian police say a man armed with a firearm and possibly explosives has barricaded himself on a bus with around 20 people on board in the town of Lutsk in north western Ukraine.

A statement from local police says police are on the scene.

Ukrainian media report police received an emergency call saying a man with a gun and explosives had taken over the bus and that several guns shots were heard earlier.

Police are reportedly negotiating with the man by phone.

A report from the national newspaper Ukrainskaya Pravda says police have found posts online from the man where he writes about his “dissatisfaction with the system in Ukraine”.

Ukraine’s president Volodymyr Zelenskiy has commented on the hostage taking calling it “alarming” and saying police are doing everything to resolve it without casualties.

Zelenskiy in his official Telegram account said he was taking the situation under his personal control. He repeated reports that they may have been already been some shooting, writing that “gunshots were heard” and that the bus was “damaged”.

“Everything is being done so that the situation is resolved without casualties. I am keeping track of events under my personal control,” he wrote.

A deputy interior minister, Anton Gerashchenko has written on Facebook that Ukraine’s interior minister Arsen Avakov has flown to Lutsk to oversee the situation.

Gerashchenko confirmed that around 20 people have been taken hostage on the bus.

The hostage-taker has said he is armed and that the bus is rigged to explode. Negotiations are being held.

Gerashchenko wrote that the hostage-taker forced the hostages to call the police at 9:25 a.m. local time and introduced himself as “Maksim Plokhoi”— ‘Plokhoi’ in Russian means “Bad”.

Gerashchenko writes that on the internet they have found a book by a “Maksim Plokhoi” called the “Philosophy of a Criminal”.