An airbag system includes an airbag having a main portion having a first periphery. The main portion is inflatable in an inflation direction to a first thickness. An extension extends from the main portion and has a second periphery spaced from the first periphery. The extension is inflatable in the inflation direction to a second thickness. The first periphery and the second periphery define a gap therebetween. A depression is disposed between the main portion and the extension at the gap and the depression has a third thickness in the inflation direction less than the first thickness and the second thickness. The extension and the depression may receive a head of an occupant during an oblique impact, in which the head of the occupant may avoid the main portion of the airbag.