Mortar shells fired from the Gaza Strip on Friday crashed into an Israeli border community, killing a man in his garden and wounding three other people, officials said. Israel retaliated with missile strikes that left five Hamas militants dead.
The violence added pressure on Egyptian-led attempts to halt clashes between Gaza militants and the Israeli military.
Gaza's ruling Hamas movement claimed responsibility for the mortar fire on Kfar Aza, a communal farm in southern Israel.
Hours later, Israeli aircraft fired missiles that slammed into two Hamas police stations in southern Gaza, killing five militants, Hamas and Gaza health officials said.
The Israeli military confirmed the airstrike and said it was responding to attacks on Israel.
Palestinian militants frequently fire crude rockets and mortar shells into southern Israel from Gaza; 14 people have been killed since late 2001.
"Hamas is clearly in control of the Gaza Strip and responsible for all hostile fire into Israel. We hold it accountable for today's attack and the murder of our civilian," said David Baker, an Israeli government spokesman.
Abu Obeida, a spokesman for Hamas' military wing, said militants had targeted an Israeli military position, but the mortar shell went astray.
Dozens of residents milled around the tidy lawn where the 48-year-old Israeli's body lay. Shrapnel pocked the front of his house. His identity was not disclosed because one of his four children had not yet been notified of his death.
Israeli rescue officials said three people were wounded by shrapnel.
The military said Friday that Palestinian militants have fired 1,950 mortar shells and rockets at Israel since the beginning of the year -- almost equal to the amount fired in all of 2007.
The attacks often provoke Israeli airstrikes and ground incursions, although hostilities have ebbed since more than 120 Palestinians were killed in a flare-up of violence two months ago.