A man and a woman are dead after the motorcycle they were travelling on crashed near Wellington's Terrace Tunnel this afternoon.
The tunnel was closed for almost four hours, causing major delays for traffic, but reopened at about 4.30pm.
Police cannot say how many vehicles were involved in the crash, but said the motorcycle made contact with the concrete barrier in the middle of the road.
The tunnel and a section of the motorway was closed in both directions, bringing drivers to a near standstill on most of the central city's roads.
The Transport Agency said the road was now completely clear.
Police said they were still interviewing witnesses, and its serious crash squad was investigating.