Four people have been arrested in Sweden on suspicion of plotting terror attacks, the Swedish Security Service told CNN Sunday. An art gallery in central Gothenburg was evacuated shortly before Saturday midnight local time, police said, but declined to say whether it was connected to the arrests. A party was going on at the Roda Sten gallery at the time. Police have a “number of extra police officers” on the streets of Gothenburg, Edberg said. Stockholm was hit by a suicide bombing in December. The attack on the capital, Sweden’s first suicide bombing, wounded two people in a district full of Christmas shoppers.