A critical incident investigation is underway after a man died and his former de facto was seriously injured at Blackalls Park.

Police were called to the Railway Parade home around 10pm last night after a domestic dispute between the two escalated.

The 29-year-old man was pursued briefly by police before he pulled the Ford Falcon over and did a u-turn.

He then accelerated toward the house and crashed through the front fence, knocking down the 32-year-old woman before slamming into a tree at up to 100km/h.

The man died at the scene while the woman remains in the John Hunter Hospital after undergoing surgery for a broken leg.

Neighbour Katie Wright says three young children witnessed the horrifying incident.

“There was two coppers out the front, there was some kids out the front and his ex I think and her sister, and they’ve all jumped out of the way, except he got the ex and the oldest boy pushed two of the kids out of the way.”

The children are currently being cared for by relatives.