The crash in Canada's capital city between a double-decker bus and a Via Rail train occurred about 8:48am local time (1.48pm BST)
CBC News reports all of Ottawa's emergency responders are heading toward the scene.
All the dead and injured were on the bus, authorities said.
More top news
Schools in London, Brighton and Newcastle were among those closed after bogus security threats.
The World Health Organization said postponing the 2016 Games would not 'significantly alter' the spread of the Zika outbreak.
Employment Minister Priti Patel has launched a scathing attack on the government's 'chaotic' immigration controls.