Police have gathered several intact cooking gas canisters from the three rudimentary explosive devices that went off in Athens early Monday and are hoping they may be able to recover clues that will help them identify the assailants.

One person suffered minor burns in the attacks at the offices of the Foundation for Economic and Industrial Research (IOBE), a branch of the Environment Ministry and the political office of the government’s general secretary for transparency, Giorgos Sourlas. The attacks occurred between 3 a.m. and 8 a.m.

Apart from examining the unexploded gas canisters, police also collected footage from CCTV cameras in the hope of uncovering more clues. No group had claimed the attack by last night.

A 62-year-old retired doctor who lives next to Sourlas’s office was slightly injured in the explosion. She was taken to the hospital with her husband, who suffered smoke inhalation.