The Israeli army said its troops shot dead four heavily armed men on the border with Gaza early on Saturday after one of them allegedly climbed the separation barrier and threw a grenade.
There have been frequent clashes along the Gaza border since the Palestinians began organising regular mass protests there in March last year but Saturday's exchange was unusual because of the weaponry the army said was involved on the Palestinian side.
"The terrorists were equipped with AK-47 assault rifles, RPG grenade launchers and hand grenades," the Israeli army said.
It released photographs of the weapons laid out on the ground.
"The army opened fire after one of the terrorists scaled the barrier and hurled a grenade at the soldiers," an army spokeswoman said.
No casualties were reported in Israeli ranks.
Military spokesman Jonathan Conricus said the men's mission was unclear but that a large-scale attack against soldiers or civilians had been prevented.
None of Gaza's Palestinian militant groups claimed the dead men as members. Mr Conricus said the military was trying to determine their affiliation.
Hamas, the Palestinian group that rules Gaza, denied involvement and said it was an "individual act by angry youths".
"The occupation is responsible for the state of anger and pressure inflicted on our people due to the continued siege on Gaza," said Abdel-Latif Al Qanou, a Hamas spokesman.
The Palestinian Wafa news agency reported that Israel bombed two areas along the border in the central Gaza after the shootings. On Friday, two Palestinians were injured by Israeli fire along the border east of the southern city of Khan Younis, Wafa said.
Palestinian demonstrations at the Gaza border to demand the lifting of Israel's more than decade-old blockade have often led to violence and a deadly response from the Israeli army.
At least 301 Palestinians have been killed by Israeli fire in Gaza or the border area since March 2018, the majority during the demonstrations.
Seven Israelis have also been killed.
The protests have declined in intensity in recent months following a truce brokered by UN officials and Egypt.
Under the truce, Israel agreed to take steps to ease its blockade in return for calm on the border.
Sporadic violence has continued but the Israeli army has said most of it has consisted of lone-wolf attacks.
On August 1, a Palestinian seeking to avenge his brother's death by Israeli fire entered Israel from Gaza armed with a Kalashnikov assault rifle and hand grenades. He was killed and three Israeli soldiers wounded, the army said.
Saturday's shooting came as Israeli forces continued their search for the culprits behind the fatal stabbing of a teenaged soldier whose body was found near Hebron in the occupied West Bank on Thursday. There was no claim of responsibility for the attack, which was praised by Hamas and the Iran-backed Palestinian militant group Islamic Jihad.
Prime Minister Benjamin Netanyahu is widely seen as wanting to avoid a major flare-up in the Palestinian territories as Israel prepares for a snap general election on September 17, its second this year.
But he is likely to face political pressure to act firmly against any significant attack.
Israel and Hamas have fought three wars since 2008.
