Sergeant Matt Lee, of Dunedin, said police, Hato Hone St John and fire crews responded to a medical event on the southern motorway at 2.22pm yesterday.
A 73-year-old man had pulled over to the side of the motorway after experiencing a heart attack.
The motorway was reduced to one lane while emergency staff attended and the man was transported to Dunedin Public Hospital, Sgt Lee said.
At 3.40pm, due to the congestion caused by the event, three cars collided in the southbound lane of the southern motorway, near Green Island.
Sgt Lee said traffic been built up by the previous incident, further along the motorway.
The front vehicle came to a stop, with the following two vehicles failing to stop in time, he said.
They were driven by a 35 year-old man, 29-year-old woman and a 29-year-old male.
The scene was cleared and both lanes were reopened at 4.14pm.
Meanwhile, at 4.32pm, emergency services responded to a nose-to-tail collision on the southern motorway, this time near the Saddle Hill onramp.
The southbound lane was closed until the vehicles had managed to leave the motorway.
There were no reports of serious injuries, Sgt Lee said, but one of the drivers told police on the phone he had ‘‘broken his thumb.’’