At least 34 people have been killed and more than 200 injured after government war planes carried out air raids on Douma, the rebel-held suburb on the outskirts of Damascus, activists told Al Jazeera.

Activists in Douma told Al Jazeera that air strikes continued through Sunday afternoon, adding that at least four buildings collapsed earlier during the day.

The UK-based Syrian Observatory for Human Rights placed the death toll from Saturday's air raids at 34, while local activists reported that at least 37 were killed. At least five children were among those killed.

The death toll is expected to rise, with Syria's Civil Defence, a local NGO, saying they are still rescuing people from under the rubble.

The Observatory said government war planes and helicopters hit several residential areas in Douma on Saturday evening. Douma is located in Eastern Ghouta and is part of the Damascus suburb province.

The Observatory reported the use of barrel bombs on both Douma and Daraya, which is located in Western Ghouta.

Activists told the Observatory that surface-to-surface missiles were also used by government forces in those areas.

In a statement released on Saturday night, the Syrian Civil Defence organisation said airs raids on Douma over the past week have killed more than 200 people and wounded more than 400 others - mostly women and children.

The group called upon international organisations and human rights groups to act immediately as it declared Douma as a "disaster town".

On August 16, at least 110 people were killed while over 300 were injured when government warplanes hit a crowded marketplace in Douma.

The market attack was condemned by the UN humanitarian chief, Stephen O'Brien, who said he was "horrified by the total disrespect for civilian life in this conflict".

At least 6,673 air strikes were recorded during the month of July, including 3,654 barrel bombs dropped by government helicopters on 13 out of 14 Syrian provinces, the Observatory said in a report on August 1.

Damascus suburbs and Idlib province were the most targeted provinces, according the Observatory, which has a network of activists on the ground.

At least 791 civilians were killed due to these air strikes, including 207 children below the age of 18. At least 3,000 others were injured while thousands were forced to flee their homes.

The UN has said that some 250,000 people have been killed since 2011 and an estimated 7.6 million are internally displaced.