Syrian activists say government warplanes again bombed the country's commercial capital early Monday, killing five people including three children.

The London-based Syrian Observatory for Human Rights and the opposition Local Coordination Committees said the early morning strikes destroyed two buildings in the southern part of the city. Amateur video claimed to show survivors and others digging through the rubble for victims.

Other video from Homs, shown on the Al Jazeera television network, showed smoke rising from parts of the city, amid reports of more shelling and fighting there.

The violence takes place as the United Nations' and Arab League joint envoy for Syria, Lakhdar Brahimi, is to brief the U.N. Security Council on his recent talks in the region. Brahimi visited Syria this month, meeting with Syrian President Bashar al-Assad and opposition representatives.

The Syrian conflict is expected to be one of the biggest issues when the United Nations General Assembly gets underway Tuesday in New York.

On Saturday, Brahimi and U.N. Secretary-General Ban Ki-moon discussed how to address what a U.N. statement called the “appalling levels of violence” in Syria. They said they hoped the U.N. session will be an opportunity to increase support for addressing the grave humanitarian situation and its impact on neighboring countries.

Eighteen months of fighting between Syrian government forces and rebels opposed to Mr. Assad has left about 20,000 people dead.