BEIRUT -- An Israeli strike in Syria on Sunday killed the son of a slain top Hezbollah commander and at least five other fighters in a move that could ratchet up tensions with the powerful Lebanese Shiite movement, which recently boasted of rockets that can hit any part of the Jewish state.
Hezbollah militants in towns and villages along the border with Israel went on high alert, said an official from the group. In the Shiite-dominated areas of south Lebanon and Beirut, the streets emptied quickly as residents feared an escalation. Hezbollah-run al-Manar TV warned that Israel was "playing with fire that puts the security of the whole Middle East on edge."
In a statement issued to the media, Hezbollah identified one of the six slain men as Jihad Mughniyeh, the son of Imad Mughniyeh, a top Hezbollah operative assassinated in 2008 in Damascus. Hezbollah blames Israel for the killing and has long vowed to avenge his death.
The younger Mughniyeh is one of the most prominent Hezbollah officials to die in Syria since the group entered the fray in 2012, fighting alongside President Bashar Assad's forces against the Sunni-led rebellion.
The dead also included another senior Hezbollah commander, Mohammed Issa, and at least one Iranian national with the group, the statement said.
The Britain-based Syrian Observatory for Human Rights said the slain Iranian belonged to the Revolutionary Guards. The group, which obtains its information from a network of activists on the ground, said the Israeli strikes hit two vehicles and a home. It said the fighters were in the area to plan attacks along the Israeli-controlled frontier.
Other Hezbollah officials said Sunday's strike targeted two Hezbollah vehicles as fighters were inspecting positions in the Golan Heights, close to the Israeli-controlled frontier, in an area known as Mazrat al-Amal. Israel seized part of the mountainous Golan Heights plateau from Syria during the 1967 Mideast war.
"While a group of Hezbollah fighters were on a field inspection of the town, Mazrat al-Amal, ... they faced rocket shelling from helicopters of the Israeli enemy, leading to the martyrdom of a number of holy warrior brothers, whose names will be announced once their honourable families have been informed," the Hezbollah statement said.
Israel's military did not comment on Sunday's incident.
A Syrian activist said Hezbollah was widely rumoured to be training pro-Assad militiamen and Syrian government forces near the area of the strikes. The activist, who uses the name Abu Omar, said Mazrat al-Amal was close to rebel positions, and that they had obtained the information from people there.
Israel and Hezbollah fought a devastating war in 2006, but since then have largely shied away from direct confrontation. On Thursday, however, Hezbollah's leader, Hassan Nasrallah, boasted that the group's rockets could hit any part of Israel and threatened to invade the Galilee region of northern Israel in the next war between the two bitter foes.
Lebanese political analyst Imad Salamey said Hezbollah's hands could be tied because it is so heavily invested in Syria. "It's an awkward situation," he said.
He said Hezbollah was unlikely to open up a second front in Lebanon while so many of its fighters are bogged down in Syria, and that it probably would not retaliate from Syria because it "invites increasing involvement by Israel to attack its operation inside Syria."
"It does not have much to work with," Salamey said.
Since Syria's conflict began in March 2011, Israel has carried out several airstrikes in Syria that have targeted sophisticated weapons systems, including Russian-made anti-aircraft missiles and Iranian-made missiles, believed to be destined for Hezbollah.
The last such airstrike was in early December, when Israeli warplanes struck near Damascus' international airport, as well as outside a town close to the Syria-Lebanon border.
Jihad Mughniyeh was born in 1989, making him either 25 or 26. Hezbollah officials said Mughniyeh was one of the Hezbollah fighters tasked with overseeing operations in the Golan Heights.
He was a Hezbollah student activist at the Lebanese American University, and took on a more prominent role after the death of his father. His photograph has been taken with Nasrallah, the group's leader, and with the powerful Iranian Gen. Ghasem Soleimani, highlighting his prominence within the group.
The officials spoke on condition of anonymity because they were not authorized to speak publicly.
Associated Press writer Bassem Mroue in Beirut contributed to this report.
