Roseburg (United States) (AFP) - Thirteen weapons have been recovered from the gunman behind the mass shooting at a US community college, and all were purchased legally, officials said on Friday.

"So far we have recovered 13 weapons. Six were recovered at the school, seven recovered at the shooter's residence," said Celinez Nunez, an agent with the US Bureau of Alcohol, Tobacco, Firearms and Explosives.

"All were traced to a federal firearms dealer," she told a news conference a day after the shooting in Roseburg, Oregon that left 10 dead including the shooter.

"In addition to the weapons recovered, we also were able to recover a flak jacket lying next to the rifle at the school, and it had steel plates with five magazines," Nunez said.

"An additional amount of ammunition was also recovered at the apartment."

Though police have yet to formally release his name, the gunman has been widely identified as Chris Harper Mercer, 26.

The bloodshed in Roseburg prompted an impassioned new plea for gun control by President Barack Obama, who said Americans had become "numb" to the horror of mass shootings.