Israeli forces have staged an airstrike on Lebanon's capital of Beirut. The attack, which came as hostilities escalate between Israel and the Lebanon-based Shia Muslim group Hezbollah, appears to be the first within the Beirut city limits.

Reuters news agency says the airstrike hit an apartment building in the Kola district early Monday.

It reports that a Palestinian militant group said three of its leaders were killed in the attack.

Video distributed by the Associated Press shows ambulances, fire engines and many people gathering near a building hit in the strike.

Many of the previous Israeli attacks were carried out in southern Lebanon and Beirut's southern suburbs, where Hezbollah has strongholds.

Monday's attack appears to be the first Israeli strike within the Beirut city limits since Israel launched a series of attacks against Hezbollah in Lebanon.

It also comes one day after Israel announced it had attacked targets linked to the anti-government Houthi group in Yemen.