Israeli air strikes took down two of Gaza's tallest apartment and office buildings overnight between Monday and Tuesday.
In one case, a building that housed seventy families, as well as offices and a shopping complex, was demolished. It was known as the Italian Compound, or Little Italy. The blasts wounded 20 people, Gaza health officials said.
Al Jazeera said that the IAF fired three warning missiles before the nighttime air strike on the Italian Compound.
The 13-story building contained 11 floors of residential units and two floors of commercial offices and a coffee shop. Those floors also host the offices of the Ministry of Public Works and offices belonging to the political wing of Hamas movement, reported Al Jazeera.
Witnesses said that residents had fled the building after the Israeli army sent them pre-recorded warning messages.
"The army told them to leave immediately and they all ran out into the street to find shelter," one told AFP.
Shortly afterwards, warplanes fired on the 14-storey Al-Basha building in the upscale western Rimal neighbourhood, causing massive damage and wounding another 15 people, witnesses and medics said.
Part of the building was used by Sawt Al-Shaab radio, or "Voice of the People", run by the Popular Front for the Liberation of Palestine (PFLP).
Israel had no immediate comment on Tuesday's attack.
It is not clear if both buildinga collapsed completely or only partially. A photograph published Tuesday morning showed a building that was still standing after about half of it had been shaved off vertically. Residents of nearby homes have reportedly evacuated their residences, in fear that the tower will collapse.
Two days ago, an IAF strike destroyed the Zafer Tower 4 in Gaza, described as being 12 stories tall.