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
One of the six survivors of a horror plane crash which killed 71 people has appeared on camera to thank his supporters.
Giraffes could disappear from the planet if current rates of extinction continue, it has been warned.
Foreign Secretary Boris Johnson has been filmed accusing British ally Saudi Arabia of "puppeteering" in the Middle East.