The hostage taker who was detained in Lutsk had firearms and grenades, Ukraine's Interior Minister Arsen Avakov said.

"No one was wounded. No other explosives were placed in other places. The detainee really had a functioning pistol, a functioning machine-gun, a combat grenade. There was a threat. It's over now," the minister was quoted as saying by the Interior ministry press service.

According to earlier reports, the man who held hostages in a bus in Lutsk for more than 12 hours surrendered.

Avakov later said the hostage taker had gotten out of the vehicle after a relevant agreement was reached with him. "He got out, [Ukraine's National Police First Deputy Chief] Gen. [Yevhen] Koval and another two of our officials got out after him. He was detained, SBU officers took security measures, the hostages got out after that," the minister told reporters on Tuesday.

"There was one unpleasant moment when the terrorist fired a shot at Mr Koval [...] It was a stressful moment for us, but we managed to bring him back to the negotiations," Avakov said.

The National Police said the bullet missed the deputy chief of the National Police and he was not wounded.