An Israeli missile strike on Syria's capital Damascus on Saturday killed four members of Iran's elite Revolutionary Guards, including the head of the force's information unit, a security source in the regional pro-Syria alliance told Reuters.

In Tehran, the Revolutionary Guards named four military advisers who were killed in the Israeli strike, but did not give their rank, and said further details would be announced later. Iranian state television said the targeted building was the residence of Iranian advisers in the Syrian capital.

There was no immediate comment from Israel, which has long pursued a bombing campaign against Iran's military and security presence in Syria. It has shifted to deadlier strikes in the wake of the Oct. 7 attack on Israel by militants of the Iranian-backed Palestinian Islamist group Hamas from Gaza.

Syrian state media reported an Israeli "aerial attack" on a building in the Mazzeh neighbourhood of Damascus and said Syrian air defences had shot down a number of missiles.

The security source, part of a network of groups close to Syria's government and its major ally Iran, said the multi-storey building was used by Iranian advisers supporting President Bashar al-Assad's government, and that it was completely flattened by "precision-targeted Israeli missiles".

The source said a fifth person was also killed but could not immediately identify the nationality.

Essam Al-Amin, head of the Al-Mowasat Hospital in Damascus, told Reuters that his hospital had received one corpse and three wounded people, including a woman, following Saturday's attack.

A Reuters witness in Mazzeh saw ambulances and fire trucks gathered around the site of the strike, which had been cordoned off. Rescue operations for people stuck under the rubble continued through the day.

Palestinian Islamic Jihad, an Iranian-backed Palestinian faction present in Syria and Lebanon, condemned Saturday's air strike but told Reuters that none of their members were wounded, dismissing reports that some were at the bombed-out building.

Iran and its military allies in Syria have entrenched themselves in wide areas of eastern, southern and northern Syria and in several suburbs around the capital, both to shore up Assad against domestic foes and encroach on arch-enemy Israel.

In December, an Israeli air strike killed two Guards members, and another near Damascus on Dec. 25 killed a senior adviser to the Guards who was overseeing military coordination between Syria and Iran.

Israel responded to the shock Hamas assault on Oct. 7 by launching a devastating air and ground war in Gaza with the aim of eradicating its ruling Islamist group. The conflict has reverberated across the Middle East with violence surging in Syria, Lebanon, northern Iraq and in the Red Sea.

In Lebanon, the country's heavily armed, Iranian proxy Hezbollah as well as local wings of Palestinian militant groups have fired rockets across the border at Israel in solidarity with Palestinians in Gaza.

On Saturday, an Israeli strike in south Lebanon killed two members of Hamas as they were travelling in their car, three security sources told Reuters.