Heavy artillery fire on Gaza escalates violence as clashes between Arabs and Jews rock Israeli cities

Gaza came under heavy artillery fire early Friday morning, amid reports - later conclusively denied - that the Israeli army had launched a possible ground invasion of the Strip.

An army tweet, which said simply "IDF air and ground troops are currently attacking in the Gaza Strip" -- which coincided with the start of a sustained new round of artillery and airstrikes -- led many news
organizations to report that a ground war, much-discussed in Israeli media on Thursday, was underway.

A clarification came about an hour or so later. "There are currently no IDF ground troops inside the Gaza Strip," army spokesman Lt. Col. Jonathan Conricus told CNN early Friday local time.

United Nations officials inside Gaza said dozens of people had fled their homes in the north and east of the enclave to seek refuge in schools - belonging to the United Nations relief agency for Palestinian refugees - which are considered designated emergency shelters.

Just a few kilometres away, residents in the Israeli town of Ashkelon were fleeing to their bomb shelters again, as sirens wailed warning of a fresh barrage of rockets.

Earlier in the day, Israel's defense minister Benny Gantz warned that Israel has "many, many more targets" and no time limit on its military operations against Gaza, as the Israeli military and Palestinian militants continued to exchange deadly airstrikes and rocket bombardments.

Israel has called up 7,000 army reservists so far, he added. Most analysts believe that the current build-up of a single division's worth of armor and infantry is not sufficient to conduct such a major incursion.

Militants in Gaza have fired more than 1,750 rockets toward Israel since the latest flareup began Monday afternoon, of which hundreds have failed or been intercepted by Israel's Iron Dome defense system. Israel has responded with devastating airstrikes in Gaza.

Israel's bombing campaign in Gaza has now killed at least 109 people, including 28 children and 15 women, the Gaza-based Palestinian Health Ministry reported Thursday. At least 621 people have sustained injuries as a result of Israeli airstrikes this week, the Health Ministry added.

Seven Israelis have been killed and more than 200 have been injured since Monday, the Israeli military said. A six-year-old boy was killed Wednesday when a rocket fired from Gaza struck a residential building in Sderot, according to an emergency responder.