The mishap occurred last night when the ambulance going from Bhusaval to Nagpur via Amravati collided with a private tourist bus coming from the opposite direction at Pachgaon intersection in Kondghali, about 60 kms from here, they said.
The two seriously injured persons were rushed to Government Medical College hospital for treatment.
The deceased include two women.
The bus driver was arrested after the accident, police said, adding that a case has been registered in this connection.