JERUSALEM — Israeli infantry and armored forces launched a ground push into the Gaza Strip on Thursday night, escalating an offensive against the Islamist militant group Hamas after efforts to broker a cease-fire failed to achieve a breakthrough.
The operation raised the prospect of heavier civilian casualties in Gaza as Israeli forces moved in under cover of a fierce artillery barrage and faced possible urban combat with Islamist militants.
At least 213 Palestinians have been killed and more than 1,600 wounded since Israel launched a bombardment campaign across the Gaza Strip last week in response to rocket attacks from the coastal enclave. According to the United Nations, nearly 80 percent of the casualties have been civilians.
A statement from the office of Prime Minister Benjamin Netanyahu said he'd authorized a ground operation "to strike at terror tunnels penetrating Israel from the Gaza Strip."
"The prime minister and defense minister have instructed the army to be prepared for broadening the ground operation," the statement said.
Earlier Thursday, the army said it had foiled an infiltration attempt by 13 Hamas militants through a tunnel dug into southern Israel, striking them from the air after they emerged into Israeli territory.
Announcing the ground operation, Brig. Gen. Motti Almoz, the chief army spokesman, said that "large ground forces, with massive support from the air force, naval forces and with broad intelligence support, are now taking control of objectives in the Gaza Strip, acting against tunnels, acting against infrastructure and terror operatives."
"I ask the residents of the Gaza Strip to evacuate the areas where the Israel Defense Forces are operating," Almoz added. "The IDF is operating there with very great force."
The Israeli army has in recent days scattered leaflets and sent automated phone messages warning Gaza residents in various areas to vacate their homes in advance of stepped-up attacks.
Hamas spokesman Fawzi Barhoum said Israel "will pay dearly" for the assault. "Hamas is ready for a confrontation," he said.
As the ground operation got under way, militants in Gaza fired a volley of rockets at the Tel Aviv area, but no casualties were reported. One Israeli has been killed and several wounded since the Israeli offensive started July 8.
Thousands of Israeli soldiers had massed on the border with Gaza in recent days, waiting for the order to go in.
Israel had called up 48,000 reserve soldiers, and later Thursday the Cabinet authorized the military to call up 18,000 more, the military said.
The ground operation came hours after Israel and Hamas had agreed to a "humanitarian pause" requested by the United Nations to allow Gaza residents to stock up on supplies and seek medical care. Thousands took advantage of the lull to stand in line at banks and produce stalls.
The ground push was ordered after an Egyptian cease-fire plan failed to take hold, rejected by Hamas. Intensified diplomatic contacts continued in Cairo on Thursday, but there was no breakthrough toward achieving a deal.
Hamas has insisted that any cease-fire plan include lifting Egyptian and Israeli border closures imposed on Gaza, particularly the Rafah border crossing to Egypt, for the passage of people and goods.
The group has also demanded that Israel release former prisoners it rearrested in the West Bank last month during a crackdown on Hamas that followed the abduction and killing of three Israeli teenagers in the territory. Israel blamed the slayings on Hamas, which did not claim responsibility for the kidnapping.
Egypt appeared to be taking on the main mediation role between Israel and Hamas, despite differences between the two sides over who would be an acceptable intermediary. According to Egyptian media reports, the Israeli delegation and representatives of Hamas sat in separate rooms as Egyptian officials shuttled between them.
Hamas has been cool to mediation by Egypt because that country's president, Abdel-Fattah el-Sissi, is hostile to the Islamist group, which has close ties to Egypt's Muslim Brotherhood. Hamas prefers Qatar or Turkey as a go-between, both of which are less acceptable to Israel.
Palestinian Authority President Mahmoud Abbas met el-Sissi in Cairo on Thursday, a day after holding talks with Moussa Abu Marzouk, the second-ranking leader of Hamas, and he was scheduled to go on to Turkey.
Netanyahu has blamed Hamas for civilian deaths, accusing it of using civilians as human shields and storing weapons in residential neighborhoods.
The United Nations Relief and Works Agency, which provides assistance to Palestinian refugees, said Thursday that it had found 20 rockets hidden in one of its vacant schools. It said the incident was the first of its kind in Gaza and a "flagrant violation of the inviolability of its premises under international law."
Information from the Associated Press was used in this article.