“He’s one step ahead”: Officials frustrated after latest Austin explosion

AUSTIN, Texas — Police say a fourth bomb exploded Sunday night after two men on bicycles hit a trip wire near a fence where it was located. It was the first time this type of method was used in the string of explosions that have rattled the state’s capital. Three other explosives were left on doorsteps earlier this month. The death toll is now two dead and five injured.
CBS News obtained home security video where the bomb can be heard detonating a few houses away.