Two young children are in hospital and three people are dead after a crash at Carrick.
Investigators believe the male driver of a Toyota Prado, who was not wearing a seatbelt, crossed onto the wrong side of the road.
He crashed into a silver Mazda ute that was heading towards Deloraine.
Two young children, aged 4 and 9 months, were in the Prado at the time of the crash.
The driver of the Prado and the two men in the ute were killed.
The young children were thought to be critical, but have since stabilised.
Speed was not a factor in the crash, investigators said.
The highway between Oaks Road and Illawarra Road remained completely blocked at 10am.
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Drivers have been asked to avoid the area where possible, and to use Meander Valley Road to travel between Hagley and Launceston.
Police will address media at 11.30am.
Emergency services are expected to be at the scene for a number of hours.
Police were also at the scene of a single vehicle crash on the highway near the Prospect turn-off.
No injuries have been reported.
There was heavy traffic heading towards Launceston as a result of the crash, just before 10am.
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