The Israeli military said it uncovered a new tunnel Thursday stretching from southern Gaza Strip into Israel and built by Palestinian militants seeking to stage attacks in Israel, a discovery that comes amid an escalation in violence between Israel and Gaza's militant Hamas rulers.
Gaza's health ministry reported a woman was killed in Israeli shelling that came in response to mortar fire by militants on Israel Thursday night. The fighting in recent days has been among some of the most serious violence between Gaza and Israel since a 50-day summer war in 2014.
Earlier, the military announced that a joint operation last month with the Shin Bet security service led to the arrest of a "Hamas terror operative involved in the terror organizations tunnel network."
It said the man was nabbed after crossing the border to carry out an attack and later provided detailed information about the elaborate Hamas tunnel network, the military said.
Gaza militants fired several volleys of mortars at Israel on several occasions Thursday, prompting Israeli retaliatory fire and airstrikes on militant targets repeatedly used by the Hamas and Islamic Jihad groups.
Mousa Abu Marzouk, an official with the Islamic militant Hamas group that rules Gaza, said Egypt and Qatar have intervened to try to restore calm.
Last month, Israel discovered and destroyed another tunnel dug from Gaza into Israel. The two tunnels are the first to be found since the 2014 Gaza war, sparking concerns in Israel that Hamas is rebuilding its underground tunnel network in preparation for another conflagration. Toward the end of the 2014 war, Israel destroyed more than 30 tunnels that Hamas had dug under the border. Hamas militants had used the tunnels to infiltrate Israel and carry out attacks.
The tunnel found Thursday is about 29 meters (95 feet) underground, the army said, and it was not immediately clear whether it is a newly dug tunnel or an older tunnel Israel had hit and which had been repaired. It was discovered by soldiers on the Gaza side of the border fence in a 100-meter zone that Israeli forces still operate in and patrol.
Lt. Col. Peter Lerner, an army spokesman, said Hamas militants may have fired toward soldiers because they realized Israel was closing in on its tunnel.
"Hamas is continuing to try to carry out and build this infrastructure into Israel and it's something we are not prepared to tolerate," Lerner said.
After Israel announced the discovery of the tunnel, more mortar rounds were fired at Israeli troops along the Gaza border fence, the military said.
Israel's military responded with tank fire. About an hour later, Gaza militants fired several more mortars at the area and Israeli tanks again retaliated, the military said. Shortly afterward, Gaza residents reported Israeli jets hit open areas and observation posts used by Islamic Jihad and Hamas militants.
The Hamas operative captured in April after crossing into Israel was identified as Mahmoud Atuna, 29. The military said he detailed "Hamas' construction methods, and how Hamas utilized private homes and public institutions to hide the tunnels."
The military also said he "pin-pointed several digging locations as well as tunnel shafts" for future attacks and disclosed details of the Hamas network within the Gaza Strip for the transportation of terror operatives and weaponry. The network, according to the information the captured operative provided, "includes resting areas, showers, and dining areas for the benefit of the operatives underground," it said.
Atuna also disclosed names and of other militants and information on weapons stored in Gaza homes, the military said.
Earlier in the day, the military said it had hit "terrorist infrastructure sites" belonging to Hamas. The Gaza Health Ministry said three children and a 65-year-old Palestinian suffered light-to-moderate injuries in an airstrike that hit a metal workshop in Gaza City.
The workshop's owner, Hassan Hassanin, said his well-digging truck -- which he described as the only one in Gaza that can reach a depth of 37 meters (121 feet) -- was hit.
"Why was it bombed," he asked. "I don't pose any threat to Israel's security. Israel itself knows this machine, what it does and what its capabilities are. It doesn't pose any danger to security."
Israel and Hamas have fought three wars since the Islamic militant group seized power in Gaza in 2007. In the 2014 summer war, more than 2,200 Palestinians, about two-thirds of them civilians, were killed. On the Israeli side, 66 soldiers and seven civilians were killed.
Israel and Hamas have largely observed a cease-fire since that war, but other militant groups also operate in Gaza. Israel says it holds Hamas responsible for any attacks out of the territory.
The latest escalation comes amid a months-long wave of violence that has seen near-daily attacks by Palestinians, mostly stabbings, which have killed 28 Israelis and two Americans. Some 193 Palestinians have been killed, most said by Israel to have been attackers and the rest killed in clashes with Israeli forces.