BEIRUT (AP) — Rockets slammed Sunday into two southern Beirut neighborhoods that are strongholds of Lebanon’s Hezbollah group, wounding at least four people, security officials said.

The incident raises fears that Syria’s civil war is increasingly moving to Lebanon, whose sectarian divide mirrors that of Syria. One leader of Syria’s overwhelmingly Sunni rebels had threatened to strike Hezbollah strongholds to retaliate against the Iranian-backed Shiite group for sending fighters to assist Syrian President Bashar Assad.

Street fighting between rival Lebanese groups has been relatively common since the end of the country’s 1975-1990 civil war, but rocket or artillery attacks on Beirut neighborhoods are rare.

One rocket fired Saturday landed in the Mar Mikhael district on the southern edge of the capital, striking a car exhibit on the street and causing all four casualties. Another struck the second floor of an apartment in a building in Chiyah district south of Beirut, about two kilometers (one mile) away from Mar Mikhael. The apartment’s balcony appeared peppered with shrapnel, but no one was wounded.

The officials said it was not clear from where the rockets were fired. They spoke on condition of anonymity in line with regulations.

The state-run National News Agency said among the wounded in the Mar Mikhael blast were three Syrians. Interior Minister Marwan Charbel blamed “saboteurs” and said: “We hope what is happening in Syria does not move to Lebanon.”

An ongoing battle in Syrian town of Qusair on the Lebanese border, which government troops backed by Hezbollah pounded with artillery on Saturday, has laid bare the Shiite group’s growing role in the Syrian conflict. Hezbollah initially tried to play down its involvement, but could no longer do so after dozens of its fighters were killed in the town and buried in large funerals in Lebanon.

Col. Abdul-Jabbar al-Aqidi, commander of the Syrian rebels’ Military Council in Aleppo, appeared in a video this week while apparently en route to Qusair, in which he threatened to strike in Beirut’s southern suburbs in retaliation for Hezbollah’s involvement in Syria.

“We used to say before, ‘We are coming Bashar.’ Now we say, ‘We are coming Bashar and we are coming Hassan Nasrallah,’” he said, in reference to Hezbollah leader Sheikh Hassan Nasrallah.

“We will strike at your strongholds in Dahiyeh, God willing,” he said, using the Lebanese name for Hezbollah’s power center in southern Beirut. The video was still online on Youtube on Sunday.

On Saturday, Nasrallah vowed to help propel Assad to victory in Syria’s bloody civil war, warning that the fall of the Damascus regime would give rise to extremists and plunge the Middle East into a “dark period.”

A Lebanese investigator takes pictures at a balcony where a rocket struck an apartment in a building at Chiyah district, south of Beirut, Lebanon, Sunday May 26, 2013 (photo credit: AP/Hussein Malla)

A Lebanese investigator takes pictures at a balcony where a rocket struck an apartment in a building at Chiyah district, south of Beirut, Lebanon, Sunday May 26, 2013 (photo credit: AP/Hussein Malla)

In a televised address, he also said Hezbollah members are fighting in Syria against Islamic radicals who pose a danger to Lebanon, and pledged that his group will not allow Syrian militants to control areas along the Lebanese border. He pledged that Hezbollah will turn the tide of the conflict in Assad’s favor, and stay as long as necessary to do so.

“We will continue this road until the end, we will take the responsibility and we will make all the sacrifices,” he said. “We will be victorious.”

The Hezbollah leader’s comments offered the clearest public confirmation yet that the Iranian-backed group is directly involved in Syria’s war. They also were Nasrallah’s first remarks since Hezbollah fighters have pushed to the front lines of the battle for the strategic Syrian town of Qusair near the Lebanese frontier.

The Syrian conflict poses a threat to the stability of Lebanon, and the fighting next door has repeatedly spilled over the border. For the past week, Assad’s opponents and supporters have been clashing in the Lebanese port city of Tripoli, using mortars, grenades and machine guns to attack densely populated areas.

Syria’s main opposition group, the Syrian National Council, slammed Nasrallah’s speech as an “an attempt to pit the Lebanese people against their Syrian brothers and sisters who have revolted against the brutal dictator.” In a statement issued Sunday, it said his speech “has the potential for serious ramifications in the region.”

“It explicitly declares Iranian interests as superior to the basic, inherent rights of people across the region,” the statement said.

Copyright 2013 The Associated Press.