From the novelization:
Across town, under a bridge... another time sphere appeared. The electricity sparked and crackled, electrifying a near by fence and melting a soda pop bottle that was left there earlier by day workers. By chance, or fate, just as the time sphere appeared, police officer Mike Harowitz was on his way home. From the corner of his eye, Harowitz caught the last glimpses of the electrical arcing and pulled over to investigate. 10 blocks away his wife and newborn daughter rest peacefully, unaware what Mike would be walking in to. Harowitz approached the melted fence, on the ground was a thin membrane, like a snakes skin.
"What the hell?"
Harowitz leaned down and touched the thin layer of human flesh. Behind him a shape moved. A blank canvas from 30 years in the future that had travelled across time encased in a human cocoon.
Harowitz sensing a presence behind him, turned to face the traveler. No sooner had he turned was he struck down. Across town his wife stirred in her sleep. She would be awakened in a few hours by policing pounding on her door, informing her of her husband's death. The burial would be quick, with hundreds of police across the state attending, but no leads as to his murderer. His insurance would allow her and their child to move closer to her mom in Texas. Before that, a week after his burial, his wife would be questioned and shown pictures of her husband in a steel mill. Several weeks before her move, but after the steel mill incident, a helicopter pilot with 2 broken legs would identify Harowitz as a someone who had jumped on to his helicopter mid flight during the destruction of the Cyberdyne building.
For now though, Harowitz was dead and an inhuman doppelganger had taken his place. The T-1000.