Belgrade, Serbia. A gunman apparently firing at random killed eight people and wounded 14 in a series of villages in Serbia, authorities said, shaking a nation still in the throes of grief over a mass shooting a day earlier. Police arrested a suspect Friday after an all-night manhunt.

Serbian President Aleksandar Vucic called Thursday's shootings an attack on the whole nation — and said the person arrested wore a T-shirt with a pro-Nazi slogan on it but did not specify a motive.

The slayings came a day after a 13-year-old boy used his father’s guns to kill eight fellow students and a guard at a school in Belgrade, the capital.

The bloodshed sent shockwaves through a Balkan nation scarred by wars, but unused to mass murders. Though Serbia is awash with weapons left over from the conflicts of the 1990s, Wednesday’s shooting was the first at a school in the country’s modern history.

The last mass shooting before this week was in 2013, when a war veteran killed 13 people in a central Serbian village.

Public figures, politicians and experts appeared successively on TV Friday, desperately seeking to explain the tragedies. The first made the country numb with grief, while the second heightened feelings of insecurity and anxiety over what might come next. As a nationwide period of mourning began, TV screens were filled with people wearing black and music was banned from the airwaves as well as in cafes and restaurants.

“This is a moment when a nation decides whether it will go along a healing path,” Actor Srdjan Timarov said on N1 television. “The only other way is to declare capitulation.”

Late Thursday, an attacker shot at people in three villages near Mladenovac, some 50 kilometers (30 miles) south of the capital. Vucic said the assailant targeted people “wherever they were.”

“I heard some tak-tak-tak sounds,” recalled Milan Prokic, a resident of Dubona, near Mladenovac. Prokic said he first thought people were shooting to celebrate a birth, as is tradition in Serbia.

“But it wasn’t that. Shame, great shame,” Prokic added.

Police said a suspect, identified by the initials U.B., was arrested near the central Serbian town of Kragujevac, about 100 kilometers (60 miles) south of Belgrade.

Authorities released a photo showing a young man in a police car in a blue T-shirt with the slogan “Generation 88” on it. The double eights are often used as shorthand for “Heil Hitler” since H is the eighth letter of the alphabet.

Vucic said the suspect repeated the word “disparagement” but it wasn't clear what that meant.

The president vowed to the nation in an address that the suspect “will never again see the light of the day.” He referred to the attack as an act of terror and announced tougher gun-control measures, on top of ones put forward by the government a day earlier.

He called for a moratorium on new licenses for all weapons in the next two years, a review of all current licenses, longer prison sentences for those who break the rules and “fierce” punishment for anyone with illegal weapons. But first police will offer an amnesty to encourage people to hand over illegal guns — an action that has had limited success in the past.

“We will disarm Serbia,” Vucic promised, saying the government would outline the new rules later Friday.