ANN reported this yesterday.
http://www.animenewsnetwork.com/news/2014-10-08/voice-actor-iemasa-kayumi-passes-away/.79678
Aside from him playing Cobra, he was in various other series which includes Nausicaa of the Valley of Wind, and as Slayer in the Guilty Gear series.
Still hoping that Cobra will still make an appearance in the series later on.
RIP Iemasa Kayumi