A man who approached a police station in Belgrade carrying a backpack with a crossbow inside has been arrested, police said.
The arrest comes two days after a crossbow attack at the Israeli Embassy in the Serbian capital.
Police said the man crossed a barrier in front of the station and walked away quickly after being ordered to stop.
Officers then caught up with him and searched his backpack, finding a crossbow with seven arrows, several knives, and a jar with firecrackers in it.
"Motives are being investigated and a search of his apartment is being conducted," police said in a statement.
It said the suspect was not on the government's list of potential "extremists."
Police said the man claimed that he was "being pursued by the mafia and secret services."
A medical examination will be carried out, Serbian Interior Minister Ivica Dacic said in the statement, adding that further actions will be decided by the prosecutor.
Serbia has been on high alert since a member of a special police unit was shot in the neck on June 29 by a man with a crossbow outside the Israeli Embassy.
The officer opened fire and killed the attacker, identified as Milos Zujovic. The officer underwent surgery and remains in the hospital.
Authorities said the assailant was a Serbian convert to Islam. His wife, currently in Montenegro, is being questioned by police at Serbia's request.