Militants in the Gaza Strip pounded southern Israel with rocket fire on Thursday, killing three people as the Israeli military pressed forward with a second day of intense air raids and naval attacks on militant targets. With Israel threatening to invade the Palestinian territory, the heaviest fighting between Israel and Hamas in four years showed no signs of letting up. The fighting, which began Wednesday when Israel assassinated Hamas’ military chief, brought life to a standstill on both sides of the border. Gaza’s streets were mostly empty as the Israeli air force continued to strike targets. Residents across southern Israel remained huddled indoors or close to home, ordered by authorities to remain close to a network of public bomb shelters. The deaths in the southern Israeli town of Kiryat Malachi were the first in Israel since it launched its operation and raised the prospects of even fiercer Israeli retaliation. Israeli leaders have said they are prepared to broaden the operation to a ground invasion if necessary, though there were no signs of extraordinary troop movements along the border. “The military will continue acting to establish deterrence against Hamas and to return the calm,” Defense Minister Ehud Barak said during a tour of southern Israel. He praised citizens for coping with the “tough moments to come.” Following the assassination of Hamas mastermind Ahmed Jabari on Wednesday, Israeli tanks, gunboats and aircraft struck dozens of sites across Gaza. A …