BEIRUT (AP) — A large explosion shook a rebel-held Syrian town along the border with Turkey on Wednesday, killing at least five people and wounding others.

The Britain-based Syrian Observatory for Human Rights said a car bomb went off in the town of Azaz close to the offices of the Syrian interim government, which represents the opposition in rebel-held areas. The Observatory and the activist-run Azaz Media Center confirmed the toll, which was likely to rise.

The blast came as the Syrian government and the opposition resumed cease-fire talks in the Kazakh capital, Astana, that are sponsored by Russia, a close ally of President Bashar Assad.

The United States is sending a senior State Department official to the talks, and President Donald Trump and his Russian counterpart Vladimir Putin signaled greater cooperation on Syria in a phone call on Tuesday. The White House said the two discussed setting up safe zones in the country, where a civil war has been raging for more than six years.

Syrian TV said the Astana talks began with a meeting between delegations from Russia and Iran, another close ally of Assad.

Azaz is on a key opposition supply route, and is a hub for fighters and opposition activists. It also hosts people displaced from fighting elsewhere in the country. The town has been the scene of several attacks, some claimed by the Islamic State group. A huge explosion in January killed at least 50 people in Azaz.

A video of the aftermath of Wednesday's explosion posted online by the Azaz Media Center showed burnt-out cars and firefighters struggling to put out a blaze. Gunfire rang out as people gathered at the scene and ambulances arrived.

The Turkish Dogan news agency said some of the wounded were taken to the state hospital in the Turkish border town of Kilis for treatment.