It happened at about 08:25 on the A737 at Lauchlan Way, near Ayrshire College.
The Scottish Ambulance Service said one person had been freed after being trapped in a vehicle. No-one on the bus was thought to have been injured.
The college has tweeted that there may be some disruption to classes this morning due to a "major traffic incident".
Two ambulances and a special incident support vehicle were sent to the scene, the ambulance service said.
Two people have been injured after a crash involving a car and a bus in Kilwinning in North Ayrshire.