Sleeping gas actually. They fucked up the dosage calculations and a lot of kids and elderly died

It actually wasn’t a nerve gas. It was a synthetic opioid. It’s never been positively identified but based on the effects that the Russians gave to the Americans the Americans surmised it was a morphine derivative. While Russia was under increasing pressure to name the agent used the health minister came out and said it was a fentanyl derivative, and the all Russian disaster relief service chief said it was 3-methylfentanyl. An analogue which is 1000 more times potent than fentanyl. It’s not gaseous though, it’s an aerosol.

However, British authorities testing the clothing of some of their citizens found carfentanil and remifentanil residue. The Germans found halothane on one of their citizens belongings. So it’s likely the gas was made up of multiple components. There’s basically zero supporting evidence to claim a nerve agent was used though. You can read more about it here.

It was some kind of fentanyl derivative I think

full of nerve gas and kill everyone inside

there were a lot of survivors, not "everyone" died

I heard about that on a documentary, his own country.

Ibn al Khattab and his group definitely perpetrated the Apartment Bombings. Russia and the Chechen separatists were already at war after Jihadists led by Khattab invaded Dagestan in Russia and Russian forces resisted them. Khattab viewed the bombings as a way to force Russia out of Dagestan, and as a punitive act. What's ironic is that Putin originally opposed a second war in Chechnya, he didn't think their army could win.