A gunman who opened fire inside a US navy base in Washington, killing 12 people, was a full-time reservist from 2007 to 2011.

At least 12 people have died in a shooting rampage at a US navy yard in Washington DC, police said.

Gunmen have killed six people and wounded up to 10 more at a US Navy base in Washington DC, according to local reports.

A gunman has reportedly killed several people, wounding up to 10 others, and is still on the loose at a US Navy centre in Washington.