Police in central Sweden have increased security at refugee accommodation centres after two Eritrean asylum seekers were arrested on suspicion of murdering two people at an Ikea store.
Local officials feared a backlash from "dark forces" who wanted to exploit the case, police chief Per Agren said.
A mother and son died in the knife attack which took place inside an Ikea store in Vasteras on Monday.
The store has temporarily stopped selling knives following the killings.
It re-opened on Wednesday and manager Mattias Johansson said he hoped staff and customers could return to "as normal a day as possible".
Security around the store was stepped up, while police officers also strengthened surveillance at refugee camps in the region, including at the centre where the two suspects live.