Two police officers and two members of the public were injured in an explosion at a building in central Athens, Greek police said on Wednesday.
All four were taken away in ambulances, police said in a statement.
A police official who declined to be named said the explosion occurred when officers reached the building in the area of Kolonos and picked up a backpack thought to contain drugs.
Police had earlier received a call from the manager of the building notifying them of the suspected drugs at the building's entrance. The manager was also injured in the blast, which police are not treating as a terrorist act, the police official added.
This is a developing story.