When Leon Kennedy, a main protaganist throughout the Resident Evil series, enters the gun shop, Robert is attacked by zombies. Leon attempts to save Robert, but is unsuccessful and Robert is killed.
In the original version of the game, Robert is shown holding a shotgun. The zombies break through a display window and jump on him before he is able to react. If Leon kills the zombies, he can take the shotgun off his dead body.
In the on-rails shooter Resident Evil Darkside Chronicles, Robert is heard yelling "Die, Goddamnit!" while Leon and Claire (another protaganist) are outside the shop. When they rush inside, Robert is lying weaponless on the floor as a zombie takes bites out of his chest. He reaches weakly out at Leon before going limp. After killing the zombie, Leon asks Robert if he is ok before realising he is dead. There are no weapons in the shop, just some ammo, grenades, and a first aid spray.
On his character profile for Darkside Chronicles, it is stated that Robert freely gave weapons away to defenders and therefore were no weapons left in the shop to defend himself with.