By Samantha Gee of RNZ A Nelson policeman who was part of efforts to save Senior Sergeant Lyn Fleming says the moment a car hit her was like a land mine exploding. Hayden Tasker, 33, is on trial at the Christchurch High Court for murdering Fleming and badly injuring Senior Sergeant Adam Ramsay, after driving into the pair in the early hours of New Year's Day last year. Tasker has admitted three charges of dangerous driving and his defence lawyers say Fleming's death was manslaughter, arguing he was depressed and drunk at the time. They say the tragedy was a failed suicide attempt, the result of Tasker wanting to spark a police chase to end his life. On Monday, constable Jude Yeoman told the court he was standing near the toilet block in the middle of Buxton Square when he heard the engine noise of an approaching car. "I hear just this impact, this incredibly powerful impact and it's like an explosion, like a landmine or something," he said. Yeoman said the vehicle was travelling at high speed.…