Palestinian health officials in the Gaza Strip say a total of 20 people, including nine children, have been killed in fighting with Israel.
The death toll made it one of the bloodiest days of fighting in several years.
The Health Ministry did not provide a breakdown on the cause of deaths. At least seven members of one family, including three children, were killed in an explosion in northern Gaza whose origins were unknown.
The Israeli military said it struck a number of Hamas targets in response to continued rocket fire out of Gaza. It said eight militants were struck.