Syria 'toxic gas' attack kills 18 civilians: monitor

At least 18 civilians, including two children, were killed in an air strike early Tuesday that released "toxic gas" on a town in northwest Syria, a monitor said.

The Syrian Observatory for Human Rights said those killed in the town of Khan Sheikhun, in the central province of Idlib, had died from suffocation and the effects of the gas.

The Britain-based monitoring group was unable to confirm the nature of the substance, however.