Police were deployed in force to the downtown area of Croatia's second-biggest city, Split, after three men were killed in a shooting on Saturday.

Witnesses in the popular port city reported hearing a burst of gunfire. A video subsequently surfaced online showing a man walking and carrying an automatic rifle. Police did not immediately confirm the video's authenticity.

Split's mayor, Andro Krstulovic Opara, confirmed that the perpetrator was in custody.

"Such an act has not been seen in decades," Opara wrote on Facebook.

Separately, police said two people were detained.

"One of them is being linked to the offense, while the other person is likely to have useful information," police said in a statement cited by the Croatian public broadcaster HRT.

Waiting for police in a coffee shop

While officials did not immediately release details on the shooting, several Croatian media outlets reported that the shooter was a 26-year-old professional sailor and that his victims were connected to the drug trade. According to Split daily Slobodna Dalmacija, one of the alleged gunman's brothers had debts with people involved in organized crime, and members of crime clans subsequently threatened and harassed both the indebted brother and the shooter. After targeting the three men, the shooter reportedly went into a coffee shop and waited for the police.

One of the shooting victims had been convicted of a deadly hit-and-run in 2004, according to Slobodna Dalmacija. The man reportedly hit an eight-year-old girl with his motorcycle and fled the scene. He was later sentenced to three years in prison.

The authorities said they would provide more information on the case at a press conference on Sunday.

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