Police say the grandmother left the sleeping child inside her Mercedes as she went into a store on Front Street.

Police say a woman in Greenport was carjacked while her granddaughter was still in the SUV on Tuesday afternoon.

Police say the grandmother left the sleeping child inside her Mercedes as she went into a store on Front Street.

That's when police say a man, Paul Ludeman, 55, of Holtsville, drove off in the SUV with the little girl inside.

News 12 has been told a bystander named William Gorga saw what was happening, picked up the grandmother and chased the suspect on Route 25 - cutting him off near Moores Lane.

Gorga says at one point he was driving west in the wrong lane to try to get the car to pull over.

The chase covered a span of around five miles from Greenport to Southold with the good Samaritan forcing Ludeman off the road.

Authorities say the grandmother then got into the SUV and tried to get her grandchild out, but the suspect continued on with both her and child inside.

Gorga forced the driver off the road again and the grandmother and child were able to make it out safely.

"I was just focused on one thing - getting the baby - then I'm focus on getting the baby and a woman," Gorga says. "I proceed to chase this vehicle. I have no idea how fast I was going, had to be fast, but I kept blowing my horn and stuff."

Gorga says he was just in the right place at the right time and did what he feels most people would have done.

Police caught the car thief a little further down the road when the stolen vehicle slammed into a guard rail.

Witnesses say the stolen SUV was going around 70 or 80 mph as it raced through the downtowns of Greenport and Southold, where the speed limit was only 30 mph.

"To put people's lives in danger, a child's life in danger, it could have been catastrophic in a small town like this," said Austin Dixon, who works at Polywoda Beverage in Southold.

Ludeman is facing a long list of charges, including grand larceny, felony DWI and child endangerment. He has a long criminal history, including a prior arrest for driving while under the influence.