Israel launched air strikes in the Gaza Strip overnight Tuesday after Palestinian militants fired a rocket and mortar shells at the country, Palestinian officials and the Israeli military said on Wednesday.
Palestinian Authority sources said that 22 Gazans were wounded in the attack.
Palestinian medical officials said about a dozen people were slightly wounded by debris from the air strikes.
The air strikes came after the Israeli military reported that Palestinian militants on Tuesday had blown up a donkey cart filled with dynamite near the concrete wall that separates Gaza from Israel and fired several mortar rounds into Israel.
No Israelis were injured.
A Palestinian militant group that identifies with al-Qaida claimed responsibility for firing the rocket and mortar shells at Israel from Gaza, which is ruled by the Islamist Hamas movement.
Hamas security sources said the Israeli air strikes hit an airport in the southern Gaza Strip which is not in use and a Hamas training camp in the north.
An Israeli military spokesman said the air strikes were a response to the cross-border attacks from Gaza and that warplanes had targeted tunnels used by militants.
Hamas, which seized the Gaza Strip from forces loyal to Palestinian President Mahmoud Abbas in 2007, says it has reached an understanding with other militant groups to halt rocket fire.
But smaller groups have carried on firing at Israel.
Israel says it holds Hamas responsible for any attacks carried out from the coastal territory.