Reports of chemical gas attacks in 2 Syrian cities

Two chemical gas attacks have been reported in northern Syria, one in the region where a Russian helicopter was downed a day earlier, killing all five people on board.

In the first alleged attack, cylinders suspected of containing chlorine gas were dropped in residential areas in the city of Saraqeb in Idlib province, the anti-regime, voluntary search-and-rescue group Idlib Civil Defence said in a post on its Facebook page.

Russia, Syria's key military backer, has vehemently denied that a chemical attack took place. In a news release carried by Russian and Syrian state news agencies, Kremlin spokesman Dmitry Peskov said the claims of chlorine usage were fabricated by the media.

The United States is not ready to officially call the incident in Saraqeb a chemical attack, but there is growing confidence that is what happened, a senior U.S. official told CNN on Tuesday evening. U.S. officials think chlorine was likely used, the source said. Evidence points to the Assad regime because the attack came from the sky and the opposition doesn't have any aircraft, the source added.