Two people are reportedly dead and seven injured after a serious truck crash south of Christchurch on Sunday morning.

Emergency services are at the site of a serious crash on Main South Rd, Bankside, after a truck and trailer unit flipped around 8:50am.

Several other vehicles were also involved and seven people are reported to have received a range of injuries.

Five ambulances, police cars, Fire and Emergency and a rescue helicopter attended the crash.

The road is closed and motorists have been advised to avoid the area if possible.

"Due to a serious crash, the road is now CLOSED between Breedings Road and Old South Road," NZTA tweeted.

"Police officers are on-site detouring the traffic and helicopter is attending. Please continue follow directions of emergency services on-site."