Dozens of armed militants from Gaza penetrated Israel’s defenses and entered Israeli communities and towns, Israeli officials said, in a ground assault that was described as war on both sides of the Israel-Gaza border and that raised fears that hostages had been taken.
“Terrorists infiltrated into Israeli territory in a number of different locations,” the Israeli military said.
Unverified television images showed them arriving in pickup trucks and by hang glider. Israeli media reports said they had also arrived on motorcycles.
Unconfirmed reports from Gaza indicated that Israelis had been taken into the Palestinian enclave, but it was not known whether they were alive or dead.
Gaza militants seized an Israeli hostage — the soldier Gilad Shalit — from the Israeli side of the border fence in 2006. Hamas, the Islamic militant group, held Mr. Shalit for five years until he was exchanged for 1,000 Palestinian prisoners from Israeli prisons, many of them convicted of deadly terrorist attacks against Israelis. The group has also been holding the remains of two Israeli soldiers killed in the 2014 war and two Israeli citizens who had crossed by foot into Gaza.
Israel’s monthlong war against Hezbollah, the Lebanese Shiite militant organization, in the summer of 2006 also began with a cross-border raid by Hezbollah and the abduction of two Israeli soldiers.
On Saturday morning, terrified residents of southern Israeli communities were hiding in their homes on Saturday morning and reported hearing shooting in the streets and Arabic being spoken outside their windows.
The Israeli authorities instructed all residents of the southern and central areas of the country to stay next to bomb shelters and instructed those in the area surrounding the Gaza Strip to remain inside safe rooms and shelters.