A 17-year-old Russian asylum seeker was arrested Sunday in connection with an explosive device that was found near a busy subway station in Oslo, Norway.
Police were able to defuse the device Saturday night before it detonated.
Signe Aaling, chief prosecutor for Norway's PST security service, said the teen was detained on suspicion of handling an explosive, but noted that it remains unclear whether he planned to carry out an attack.
"PST is now working on finding his intentions and find out whether others are involved," she said.
Aaling added that the explosive had "limited damage potential."
The teen, who has not yet been identified, arrived in Norway with his family in 2010, according to security service head Benedicte Bjornland. Bjornland said the teen was allegedly part of "extreme Islamism" circles in Norway and was arrested based on a tip.
"It is likely that that attacks in France, Germany, Great Britain, Russia and Sweden can create a copycat effect in Norway with people with Islamic sympathies," he added.
Bjornland said attacks across Europe demonstrate how easily something like this can be carried out, prompting others to try and do something similar.
The teen's lawyer told Norwegian broadcaster NRK that her client denies any wrongdoing.
The 17-year-old has a pre-trial custody hearing scheduled for Monday.
The explosive device was discovered Saturday night outside the Groenland subway station. Authorities were forced to evacuate bars and restaurants in the area.
Norway was already on high alert because of Friday's truck attack in Stockholm, Sweden, that killed four people and injured 15.
The Associated Press contributed to this report.