The Palestinian ministry of health in Gaza says 256 Palestinians, including 20 children, have been killed in Israeli airstrikes in the past 24 hours. Another 1,788 people have been injured, the ministry reports.
The Israeli Air Force earlier released footage of its strikes on multiple buildings in the Gaza Strip where Hamas military targets are said to be located.
Information from Gaza has been scarce but pictures and footage on social media show numerous buildings including places of worship reduced to rubble.
Some show Gaza residents seeking shelter in hospitals.
Israeli authorities said they are starting to evacuate residents.