British police investigating explosive devices sent to addresses in London and Glasgow last week say a claim of responsibility has been made in the name of the Irish Republican Army, the BBC reports. The packages arrived on March 5 and 6 at three London transport hubs—Waterloo Station, and buildings near Heathrow and London City airports—and at the University of Glasgow. The London packages contained “small improvised explosive devices,” police said, one of which caught fire when opened by staff at Heathrow. Bomb-disposal officers detonated the item sent to Glasgow. Irish police have been assisting in the investigation as the packages had Republic of Ireland stamps attached to them. A joint statement from Police Scotland and the Metropolitan Police said the claim of “IRA” responsibility was received Monday by a Northern Irish media outlet. It added: “Given the packages received last week bore similarities to devices sent in the past, which were linked to dissident groups associated with Northern Ireland-related terrorism, officers were already looking at this as a line of inquiry. However, we continue to keep an open mind and inquiries continue.”