A gas canister exploded at the entrance of a large bookstore in Kita Ward, Sapporo, on Tuesday morning, in an apparent copycat crime spawned by a string of blasts for which a 51-year-old woman was arrested last month, Hokkaido police said Wednesday.
Fragments of a cooking gas cylinder were found by cleaning staff at the entrance of the Coach and Four bookstore at around 7 a.m., the police said.
No one was injured by the blast, which took place before the store opened, the police said, scattering several hundred books across the immediate vicinity.
Police also discovered more than 1,000 nails, each about 3.5 cm long, as well as the remains of a solid fuel briquette and another gas canister that had not exploded.
It was the second such incident within three days. On Sunday, a gas cylinder exploded in the parking lot of the Kita Ward Police Station, cracking the building's windows.
Despite the similarity to the string of explosions that occurred between January and April at five locations in Kita Ward centered on the police station, police said the nails and canister used in Tuesday's incident were different.
On April 30, police arrested Sanae Nasukawa, a resident of Kita Ward, in connection with the five earlier blasts. Nasukawa has been charged with setting off explosives targeting Hokkaido Prefectural Police facilities for the attacks directly against or adjacent to the Kita Ward Police Station.
Police said a charred cylinder was found on a street about 50 meters away from the site of Tuesday's explosion. The cap of a cylinder was discovered on the eaves above the store entrance.
The store's 49-year-old manager said security had been beefed up during opening hours but that his employees hadn't noticed any suspicious activity before going home at 1 a.m. on Tuesday morning.
