The apartment in which Hamas leader Saleh al-Arouri was allegedly killed by Israel was an old office used by the Palestinian Islamist organization, according to sources from the Iranian-backed Hezbollah movement in Lebanon.

The sources told dpa on Thursday that the office had always been there but it was empty for while, although recently it was used again.

Hamas is currently using another office to hold press conferences near Beirut International Airport, which is also an area heavily controlled by Hamas’ allies, Hezbollah.

Al-Arouri, the deputy head of Hamas’ political bureau, was killed on Tuesday evening in the southern suburbs of the Lebanese capital Beirut, which a Hezbollah stronghold.

Lebanese security sources said Israeli surveillance drones were heard hovering over Beirut’s southern suburbs, which is where the targeted Hamas office was located, since the early hours of Tuesday.

Hamas and Hezbollah blame Israel for al-Arouri’s killing.

Israel’s military has so far declined to comment on reports of a targeted killing. In total, seven members of Hamas and allies were killed in the attack.