Emergency services are racing to respond to a major incident unfolding in a central Auckland suburb.  Over half a dozen police cars could be seen speeding down Manukau Rd while an ambulance rushed to hospital in the opposite direction.  Armed police officers were seen blocking Arthur Street.  Emergency services could be seen rushing down Manukau Rd to the scene. Photo / Supplied  Residents on an Onehunga community Facebook page have reported hearing sirens and the Eagle helicopter buzzing overhead.  One resident believes the incident involved a firearm.  Another reported seeing police descend on Arthur St carrying rifles.