In the first mishap, a boy and a girl were seriously injured when their bike hit a bus at Raja Maidam K B Road here.
The duo have been shifted to Assam Medical College Hospital in Dibrugarh.
In another incident, a motorcycle-borne couple were injured when their bike collide head-on with a vehicle at National Highway 37 near Jorhat Bypass while they were on their way to Sibsagar from Jorhat.
The injured have been admitted to Jorhat Medical College Hospital.
The other one was admitted to Jorhat Medical College Hospital in a critical condition.