The number of deaths is likely to rise, according to the Union of Medical Care Organizations, a coalition of international aid agencies that funds hospitals in Syria and which is partly based in Paris.
The group said the village of Khan Sheikhoun to the south of Idlib had initially been hit before strikes on the White Helmets emergency services centre in Khan Sheikhoun and the Al-Rahme hospital.
"We have seen more than 40 strikes since 06h30," it said. "The toll continues to increase as do the strikes in the Idlib region as well as non-chemical attacks in Hama," the group said.
United Nations has formally launched an investigation in the aftermath of the attack. United Nations war crimes investigators said on Tuesday they were looking into an alleged chemical weapons attack on a Syrian town in Idlib as well as reports of a subsequent attack on a medical facility where injured people were being treated.
World leaders have come very profoundly come out in condemning the attack.
"Once again the Syrian regime will deny the evidence of its responsibility in this massacre. Like in 2013, Bashar al-Assad counts on the complicity of his allies to act with impunity," Hollande said in a statement on Tuesday.
France also wants an emergency meeting be held of the United Nations Security Council (UNSC) for a discussion on the gas attack.
Syrian army has formally denounced any involvement in the attack.