Syrian civilians near the war-torn country's capital were attacked Monday with suspected poisonous gas — believed to have been launched by the Syrian government, activists and rescue teams said.

More than 20 civilians, including women and children, were evacuated from a rebel-held neighborhood in the Douma district early Monday morning, Syrian Civil Defense said. The Syrian Observatory for Human Rights said at least 13 people suffered from suffocation, Reuters reported.

The Ghouta Media Center, an activist-operated media organization, claimed chlorine gas was used in the attack. Health officials said people had symptoms that "suggest they have been exposed to chlorine gas inhalation."

The team of first responders known as While Helmets, or Syrian Civil Defense, showed videos of babies who suffered complications from Monday's alleged chlorine attack.

A foul smell followed a series of bombings that hit the neighborhood, activists said.

The Syrian government was previously blamed for deadly gas attacks on its own citizens. The Syrian government and army have vehemently denied using the poisonous gas.

The most recent attack that killed at least 58 people last April prompted President Trump to launch 59 Tomahawk missiles that targeted an airbase in Shayrat, located outside Homs.

The airbase was believed to be the same place where the Syrian government launches most of its suspected gas attacks.

The Easter Ghouta suburb of Damascus has been under intensive attack. The U.N. said government forces are holding 400,000 people under siege there.

The Associated Press contributed to this report.