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The Uzbek man wanted for a truck attack in Sweden that killed four and injured 15 had applied to be a permanent resident there and was interested in extremist groups, authorities said Sunday.

Jonas Hysing, Sweden's National Police Commander, told reporters that the unidentified 39-year-old man’s application for residency was rejected last June. It was not clear why he was turned down. The suspect was supposed to leave Sweden in January, he said.

Hysing added that the suspect had “expressed sympathy" for extremist groups, including the Islamic State, Reuters reported.

In a news conference Saturday, Stockholm Police Chief Dan Eliason said authorities had already gathered intelligence on the suspect, whom he described as a “marginal character.”

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A second person was arrested in the attack, police confirmed to NBC News, though authorities offered no additional details.

Hysing said that Sweden's national bomb squad and counter-terrorism unit were being deployed to Stockholm to assist the police.

Flowers outside Ahlens department store following Friday's attack in central Stockholm Philip O'Connor / Reuters

The attack occurred on Friday afternoon when a vehicle that Reuters reported was a stolen beer truck barreled into a busy shopping district in Sweden’s capital.

Among the dead was Chris Bevington, a citizen of the United Kingdom who worked for the digital music service Spotify for five years.

Related: A Short History of Vehicles Being Used as Deadly Weapons

“We are all devastated by the untimely and tragic death of our talented, compassionate and caring son Chris,” Bevington’s father, John, said in a statement.

Two Swedes and a Belgian citizen were also killed.

A truck that crashed into the Ahlens department store in central Stockholm is towed from the site early Saturday. MAJA SUSLIN / AFP - Getty Images

Swedish Prime Minister Stefan Lofven on Saturday visited the site of the attack, saying that while the country remained in shock, “we shall take us through this together.”

“We want to have an open society in Sweden,” he said. “We shall continue with that.”

The low-tech rampage was the latest to use a weaponized vehicle to devastating effect, following similar incidents in England, France and Germany.