Mount Pleasant Police Chief Louis Alagno said at a news conference Monday that the major case unit of the state police and Westchester County crime scene experts have joined the probe.
In the chaotic moments after 20-year old Danroy Henry was shot, video taken by a Pace University student shows people are frantically trying to save the student's life hovering over him on the ground performing CPR.
Other video shows the situation seemingly out of control as students are screaming and officers with guns drawn are shouting orders.
"I can't describe to you why the driver did what he did," Alagno said.
Henry and two other passengers were in a car in a fire lane outside Finnigan's Grill at a strip mall in Thornwood when police began answering a call of a disturbance.
Based on police accounts, a Mount Pleasant officer approached the grey Altima knocking on the window.
The car, police claim, started to pull away, quickly approaching Pleasantville police officer Aaron Hess, who investigators say tried to stop the vehicle.
"Officer Hess ended up on the hood of the vehicle," Alagno said.
Hess fired into the vehicle as he was clinging to the top of the car.
Another Mount Pleasant officer then fired his weapon. Police say they do not know which shots struck Henry. The car subsequently struck a parked Mount Pleasant police car and came to rest.
At this point, officers were trying to restore order. Students were still yelling. Police say there were fights after the shooting.
"This is going to be a long hard investigation. And will be as thorough as possible. We want to identify what happened and why it happened," Alagno said.
Alagno called the Sunday shooting outside Finnegan's Grill in Thornwood "horrendous."
Meanwhile, Henry's parents are trying to cope with the loss of their son and the shocking nature of his death.
"Not only are we experiencing this great loss, but we're also beside ourselves because we just absolutely can't understand how this could happen to our son," Danroy Henry Sr. said outside the family's Massachusetts home.
Henry Sr. and his wife, Angela, had watched their son play in Pace's homecoming game against Stonehill on Saturday, attended by about 500 people.
"You're going to get the police reports. So we're going to need to do some work on our end to make sure that that's all factual. ... There are a lot of witnesses who say that that's not the version, so we need to get to the bottom of it, one way or another," Henry said.
A passenger was wounded. A third man in the back seat was not hurt. The officers involved were also treated for injuries.
The other injured officer was identified as Ronald Beckley of the Mount Pleasant town force.
It was a very sad and somber mood on the Pace University campus Sunday night.
In the glow of candlelight, students moved through campus, privately grieving the loss of 20-year-old Henry, known to friends as DJ. He was a junior football player.
"We really do miss him," one student said. "This is just a huge shock to all of us. He was a great guy."
His loss was deeply felt by the students who knew him.
They came together in a private vigil that began at the campus fitness center, moved to the football field and ended at the student center.
"We extend the deepest sympathies of our community to Mr. Henry's family and friends. We are working with the police investigation and as appropriate will share more information when it becomes available," Pace University President Stephen J. Friedman said in a statement.
Police are now focusing on the disturbance, which continued, they say, after the shooting.
Police are also trying to determine what was occurring inside the vehicle as officers attempted to stop it from leaving the shopping center.