The crash happened at about 3.30pm, on the A63 at Selby Road, Monk Fryston, near Garforth.
Police are now at the scene of the collision and have warned commuters and motorists to expect disruption as the roads in the area are "extremely busy".
Two people were taken to hospital for treatment after the bus and lorry collided today.
A North Yorkshire Police spokesman said: "Please avoid the area while emergency services work at the scene of the collision.
"The roads around Monk Fryston are extremely busy, and motorists should make alternative arrangements for their journeys."