The Wall Street Journal earlier reported that the parcels containing incendiary devices were part of a Russian operation intended to start fires on cargo and passenger planes flying to the United States and Canada.
"I understand the wish to know, the need for people to know, because we are living in a situation now where people may feel insecure. I can assure you that the pre-trial investigation is underway, it is being carried out quite intensively, with the participation of law enforcement authorities from other countries," Grunskienė told reporters at the Seimas.
"There have also been people arrested but I will not say how many, in order not to harm the investigation undergoing not only in Lithuania, but also in other countries," she added.
According to the publication, one of the parcels sent via DHL caught on fire in Leipzig, Germany, while the other started a fire in a DHL warehouse in Birmingham, the United Kingdom.
It has transpired that electric massagers containing a flammable substance were used for this. This appears to have been a "test run" to examine how to get incendiary devices on planes flying to North America, according to the Wall Street Journal.
As reported previously, both parcels were sent to the same address in the United Kingdom. They were shipped from Lithuania on 19 July. Both fires started on the night from 20 to 21 July.
The LRT public broadcaster had reported that the person who sent the parcels used a fake identity and provided an address where the sender did not live. The same individual sent more parcels but they were not transported by air, thus there was no more danger for aviation.