A gunman has shot dead 12 people, including two children, in southern Montenegro, police say.

At least some of Wednesday's deaths happened inside a restaurant in the Cetinje area following a verbal argument between guests, according to the authorities.

It was later confirmed that the attacker had killed himself.

The government has declared three days of national mourning from Thursday, with Prime Minister Milojko Spajic saying the shooting had "shrouded our country in black".

Police said the attack began at 17:30 (16:30 GMT) when a man - named Aleksandar Martinović, 45 - opened fire in the restaurant.

He killed members of his own family, two of the restaurant owner's children - aged 10 and 13 - and also the owner, according to Montenegro's police commander.

The gunman then went on to kill more people at other locations.

Interior Minister Danilo Saranovic called the incident a "consequence of disturbed interpersonal relations", according to AFP news agency.

According to police, the suspect had been drinking heavily before the attack began.

Four people were taken to hospital after being seriously wounded in the shooting.

The attacker fled but later fatally injured himself after being surrounded by police who asked him to drop his weapon, police said. He died on the way to hospital.

Writing on social media, the prime minister said: "This senseless act has caused immeasurable sadness and bitterness in each of us. There are no words of comfort."

Milojko Spajic said the country's security council would "urgently consider all options" to protect the public, including a complete ban on the possession of weapons.

Mass shootings are comparatively rare in the small Balkan nation.

In 2022, a man killed several people, including children, in Cetinje following a family dispute.