At least seven people have died, including a senior militant, as a result of Israeli airstrikes, Palestinian officials have said.
A blast was heard in Gaza City on Friday and smoke was seen coming from the seventh floor of a tall building.
The Palestinian Health Ministry said that 40 people were wounded and a senior Islamic Jihad commander and a five-year-old boy are among the dead.
The strike comes after days of tensions following the arrest of a senior militant in the occupied West Bank on Monday.
Israel had closed roads around Gaza earlier this week and sent reinforcements to the border, in anticipation of retaliation.