JERUSALEM - The Hamas militant group says seven of its members have been killed in Israeli airstrikes on the Gaza Strip, and it is vowing revenge.
In a statement, Hamas says six were killed in a single location, while a seventh died in a bombing shortly after midnight. It says that in all, nine Palestinian militants have died in Israeli airstrikes overnight. That makes Monday the deadliest day in a current round of fighting that broke out about three weeks ago.
Hamas' military wing says "the enemy will pay a tremendous price."
The Israeli military said it carried out a number of airstrikes overnight in response to continuing rocket fire out of Gaza. In all, it says militants have fired more than 150 rockets and mortars into Israel in the latest round of fighting.
Israel arrested six Jewish suspects Sunday in the grisly slaying of a Palestinian teenager who was abducted and apparently burned alive last week - a crime that set off a wave of violent protests in Arab sections of the country.
Leaders of the Jewish state appealed for calm amid signs the death was revenge for the recent killings of three Israeli teenagers.
"We will not allow extremists, it doesn't matter from which side, to inflame the region and cause bloodshed," Prime Minister Benjamin Netanyahu said in a nationally televised statement. "Murder is murder, incitement is incitement, and we will respond aggressively to both."
He promised to prosecute those responsible to the full extent of the law.
The region has been on edge since three Israeli teens - one of them a U.S. citizen - were kidnapped while hitchhiking in the West Bank last month. Last week, the teens' bodies were found in a West Bank field in a crime Israel blamed on the militant group Hamas.
Just hours after the youths were buried, Mohammed Abu Khdeir, a 16-year-old Palestinian from east Jerusalem, was abducted near his home, and his charred remains were found shortly afterward in a Jerusalem forest. Preliminary autopsy results found he was still alive when he was set on fire.
Palestinians immediately accused Israeli extremists of killing the youth in revenge. And on Sunday, Israeli authorities said the killers had acted out of "nationalistic" motives.
The suspects remained in custody and were being interrogated, authorities said.
An Israeli official said there were six suspects and described them as young males, including several minors, all of whom lived in the Jerusalem area. The official spoke on condition of anonymity because the investigation was continuing.
He said police had located a car used by the suspects. During the investigation, he said, police learned of an attempted kidnapping the previous day of a child in the same neighborhood and concluded the cases were linked. Israeli TV showed pictures of the 9-year-old boy with red marks around his neck.
Abu Khdeir's family said that the arrests brought them little joy and that they had little faith in the Israeli justice system.
"I don't have any peace in my heart, even if they captured who they say killed my son," said his mother, Suha. "They're only going to ask them questions and then release them. What's the point?"
She added: "They need to treat them the way they treat us. They need to demolish their homes and round them up, the way they do it to our children."
Abu Khdeir's death triggered violence in his neighborhood, as angry crowds destroyed train stations and hurled rocks. The unrest spread to sections of northern Israel over the weekend.
On Sunday, the situation in east Jerusalem, home to most of the city's Palestinians, appeared to be calming down, as businesses and markets reopened, and roads that had been cordoned off were reopened to traffic.
Top Israeli officials expressed concern that the charged atmosphere of recent days had led to the boy's killing.
After the Israeli teenagers were found dead, several hundred Jewish extremists had marched through downtown Jerusalem calling for "death to Arabs." Social media sites were also flooded with calls for vengeance.
Justice Minister Tzipi Livni said her ministry is investigating some of the anti-Arab incitement seen on Facebook last week.
"These things need to be cut when they are small," she told Channel 2 TV. "At this moment, everybody's job should be to lower the flames."
Cabinet minister Jacob Peri, a former head of the Shin Bet security agency, said he had met with Arab leaders in northern Israel to calm tensions. President Shimon Peres, a Nobel peace laureate, also was in contact with Arab leaders.
About 50 people were arrested in several days of demonstrations following Abu Khdeir's death, and 15 police officers and two civilians were injured, authorities said.
A 15-year-old Palestinian-American cousin of Abu Khdeir was also injured in clashes with Israeli security forces in east Jerusalem.
The boy, Tariq Abu Khdeir, who goes to school in Florida, was ordered confined to his home in Israel for nine days while police investigate what they say was his participation in violent protests - a charge his family denies.
The U.S. State Department said it was "profoundly troubled" by reports that he was beaten, and Israel's Justice Ministry launched an investigation.
As Tariq was released to his family, he was crying and appeared badly bruised, with both eyes and his mouth swollen. "I feel better. I am excited to be back home," he said.
State Department spokeswoman Jen Psaki said, "If the investigation is concluded promptly, Mr. Khudeir should be able to return to Florida as planned with his family later this month."
Tariq's parents said they plan on returning to the U.S. with their son on July 16.
Tariq, his face covered in bruises, told CBS News he was trying to run away from the clashes when Israeli security forces grabbed him.
"They punched me, they kicked me, they kicked me in my face. They made sure I wasn't able to see anything. I wasn't even breathing," he said.
"They didn't stop. They were carrying me and still kicking me and punching me. Even when I was unconscious," he said.
He said he was haunted by thoughts of his murdered cousin.
"I can still remember his voice in my head," Tariq said. It's like he's still here. Just that like nobody can see him."
The Reuters news agency reports that a video going around the Internet on Saturday "showed two Israeli border policemen holding down and repeatedly pummeled a masked youth before carrying him away. A later part of the video shows Khdeir's face with a heavy black eye and swollen lip."