GAZA CITY, Gaza Strip (AP) — Palestinian militants bombarded Israel with dozens of rockets and mortar shells Monday, while Israeli warplanes struck targets throughout the Gaza Strip in what appeared to be the most intense exchange of fire since a 2014 war.

Palestinian officials said at least three people, including two militants, were killed by Israeli fire and nine were wounded, and an Israeli airstrike destroyed the ruling Hamas group’s TV station. In Israel, the national rescue service said at least 20 people were wounded, including a 19-year-old soldier and a 60-year-old woman who were in critical condition.

Early Tuesday, Israeli media reported that a man was found dead under the rubble of a building in the southern coastal city of Ashkelon hit by Gaza rockets.

Gaza’s health ministry, meanwhile, said a 22-year-old Palestinian who was wounded in an earlier airstrike died, putting the Palestinian death toll since the current flare-up started late Sunday to 11, the majority of them militants.

The fighting cast doubt over recent understandings brokered by Egypt and U.N. officials to reduce tensions. Just a day earlier, Israel’s prime minister had defended those understandings, saying he was doing everything possible to avoid another war.

The United Nations said it was working with Egypt to broker a halt in the violence. “Rockets must STOP, restraint must be shown by all!” the U.N. Mideast envoy’s office tweeted.

U.N. Secretary-General Antonio Guterres, meanwhile, urged Israel and the Palestinians “to exercise maximum restraint,” according to a statement.

The rocket fire was triggered by a botched Israeli military raid in Gaza on Sunday. Undercover troops, apparently on a reconnaissance mission, were discovered inside Gaza on Sunday, setting off a battle that left seven militants, including a Hamas commander, and an Israeli military officer dead.

Around sundown Monday, militants launched some 100 rockets in less than an hour, the most intense barrage since the 50-day war four years ago. The outgoing rockets, which continued into the evening, lit up the skies of Gaza and set off air raid sirens throughout southern Israel.

By early Tuesday, at least 300 rockets had been launched from Gaza, the Israeli military said, adding that up to 70 of them were intercepted by the anti-missile defense system Iron Dome.

The military said warplanes, helicopters and tanks had struck over 70 militant targets, including military compounds, observation posts and weapons facilities. It also said it targeted a squad that was launching rockets.

The airstrikes and rocket barrages resumed at dawn after nearly two hours of calm.

Lt. Col. Jonathan Conricus, a military spokesman, said the army had sent additional infantry troops, rocket defense systems and intelligence units to the Gaza frontier.

“We continue to strike and retaliate against the military targets belonging to terrorist organizations in Gaza, and as for our intentions we will enhance these efforts as needed,” he told reporters.

Late Monday, an airstrike destroyed the Gaza City headquarters of Hamas’ Al Aqsa TV station. Israel had fired warning shots ahead of the airstrike, prompting the station to halt programming and replace it with a logo. Minutes later, the airstrike flattened the three-story building and the station went black.

Workers had evacuated the building after the warning shots, and there were no immediate reports of casualties.

Hamas spokesman Fawzi Barhoum condemned the bombing as “a barbaric, brazen aggression.” Ten minutes later, the station resumed broadcasts, airing prerecorded national songs.

Israel said the station “broadcasts violent propaganda” and provides “operational messaging” to militants. A five-story office building that housed Hamas media offices and another building used by Hamas’ internal security service were also destroyed. No casualties were reported.

Hamas and the smaller militant group Islamic Jihad said the rocket fire was revenge for Sunday night’s Israeli incursion. Islamic Jihad spokesman Daoud Shehab said the groups wanted “the occupation and its supporters know that the lives of our sons come with a price.”

In all, well over 300 rockets were fired into Israel by midnight, the army said. The Israeli military said it intercepted 70 rockets, and most of the others fell in open spaces. But rockets landed in the southern Israeli town of Sderot, setting off a large fire near a shopping center.