Story highlights Israel says the residential building was a Hamas command center

The airstrike injured 20 people, the Palestinian Health Ministry says

Israel also says it destroyed rocket launchers hidden near medical facility, schools

Palestinian official says nine people were killed Monday

An Israeli airstrike blasted a residential tower in Gaza on Monday night.

CNN video and Hamas-run Aqsa TV showed rockets hitting the structure known as the Italian Tower.

Residents evacuated the tower after an earlier drone airstrike known as a "knock on the roof."

The Palestinian Health ministry said 20 people were injured in the airstrike.

The Israeli military said the building housed a Hamas "command and control center."

Two days ago, an Israeli airstrike in Gaza reduced a 14-story residential building to rubble.

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Earlier Monday, the Israel Defense Forces said it had destroyed rocket launchers concealed inside a shelter for evacuees in Gaza.

The IDF said Palestinian militants had fired rockets from spots next to several civilian facilities in the Al-Shati refugee camp in northern Gaza, including the Shuhada medical facility and the Even Sina and Zlach Halif schools.

Both schools had been used as shelters for Gaza residents who had to leave their homes.

On Sunday, the IDF said it told residents in the area to evacuate to avoid injury.

In the subsequent bombing, the rocket launchers were hit, and the "rocket arsenal concealed within the facility" was destroyed, causing several secondary explosions and extensive damage, the IDF said.

It's unknown whether there were any casualties.

Hamas-run Aqsa TV reported that one person died and three people were critically injured in an airstrike on a vehicle in Gaza City.

Ashraf el-Qedra, a spokesman for the Palestinian ministry, posted on his Facebook page that nine people were killed Monday, making a total of 2,131 killed and 10,890 injured in the past 50 days.