NBC News

GAZA CITY, Gaza — The militant group that rules the Gaza Strip asked for a cease-fire hours after Israel resumed attacks on the enclave. An Israeli army spokesman Lt. Col. Peter Lerner did not say if Israel would hold fire during, adding that troops would continue demolishing militant tunnels.

And during an appearance on NBC's Meet The Press, Israel's Prime Minister Benjamin Netanyahu said that Hamas had not kept to any ceasefire agreement.

"We’ve accepted five ceasefires — Hamas has rejected every single one of them," he said.

Artillery fire and air strikes punctuated Israel's earlier announcement that it would resume fighting in Gaza, shattering a fragile peace that had allowed many Palestinians to search the rubble of their homes.

"Following Hamas' incessant rocket fire throughout the humanitarian window, which was agreed upon for the welfare of the civilian population in Gaza, the (military) will now resume its aerial, naval and ground activity in the Gaza Strip," Israel announced, adding that it had repeatedly urged residents of the Palestinian enclave not to approach "combat zones." On Saturday, Hamas rejected an Israeli proposal to extend a previous cease-fire.

A column of smoke rose into the air above Gaza City, and NBC News teams in the area reported hearing incoming artillery shells, fighter jets and air strikes immediately after the announcement at around 10 a.m. (3 a.m. ET).

Clashes soon erupted between Israeli troops and Gaza militants, according to The Associated Press. The Islamic Jihad group said one of its field commanders was killed by tank fire near the southern Gaza town of Khan Younis, the AP added.

The Israeli military said that 25 rockets had been fired at the country since midnight. Over 1,045 Palestinians have died in the 20-day confrontation, while 46 Israelis have been killed.

Israel says it is trying to prevent civilian casualties, including by sending evacuation warnings to residents in targeted areas, and blames Hamas for so many civilians being killed in the bombings. Palestinians counter that there are no safe havens in the strip. On Thursday, a U.N.-run school housing evacuees was bombed, killing 15.

Gazan authorities blamed the Israeli forces for the incident. The Israeli military said its troops were fighting gunmen from Hamas, which runs Gaza, in the area and that it was investigating.

Palestinians in Gaza returned to destroyed neighborhoods during the 12-hour truce on Saturday, which was agreed to by both sides. Some 150 bodies were found in the rubble during the window in fighting, although hundreds more could still be buried, according to Palestinian health officials.

Israel launched the operation on July 8 it says to stop rocket fire from the militant-ruled enclave, and to destroy tunnels that Hamas could use to infiltrate the country and get needed supplies.