State police believe the driver of a bus that crashed, killing five people, may have spent the previous two nights in a casino and was tired when he got behind the wheel.

The Arrowhead Coach USA bus crashed Sunday on the New York State Thruway, 16 miles south of Rochester in the western part of the state.

The bus slammed into a guardrail and plunged down a 75-foot embankment before coming to a stop, state police Maj. Mark Fischer said at a news conference Monday.

Police also released the names of the dead — all Waterbury, Conn., residents: Alexis Blondet, 16; Maikel Mota, 29; Enerolisa Polanca, 29; Ruth Restiuyo, 30; and Jasmine Santiago, 15.

The driver, William Hovan, 49, was being interviewed at a state police barracks Monday, while police in the parking lot combed the crushed bus for clues. Police initially thought Hovan's diabetes may have played a part. Passengers said he appeared to be falling asleep. He was not seriously injured and was released from a hospital Sunday night.

By Monday, police had ruled out Hovan's diabetes and mechanical failure as possible causes of the crash.

"It's our belief that he was in a casino both Friday and Saturday night," Fischer said, adding that police are trying to confirm Hovan's whereabouts.

Fischer said passengers "clearly very early on [were] aware that this driver was fatigued."

Police are meeting with Ontario County District Attorney Mike Tantillo to see if charges will be filed.

Blondet's cousin, Miguel Diaz, 30, was given the news Sunday night at Waterbury police headquarters.

"I don't believe it," he told The Hartford Courant. "I gotta see him to believe it. This ... it's like a dream or something."

Forty-four people were aboard the bus, which was traveling from Niagara Falls to Waterbury, Conn., when the accident occurred about 3 p.m. Sunday.

"It caught the guard rail, ripped off a pretty lengthy section. That guard rail then hit two other vehicles, rolling one over, knocking another down an embankment, and smashing the window out of a third," Fischer said.

"The bus became airborne, crossed the onramp, landed and slid down the embankment."

Fischer said Monday he was confident that seat belts would have helped in the Coach USA bus. The dead were found in the center of the bus and all were ejected or partially ejected.

Fischer said passengers were calling out through bus windows for help.

"It was very chaotic," he said.

At the state police barracks Monday, personal belongings including baby strollers, backpacks and shopping bags were being unloaded from the bus and put onto another bus bound for Waterbury. Coach USA was sending a bus around noon Monday to bring relatives from Waterbury to New York.

Before the crash, several passengers tried to warn the driver to pull over but he did not, Fischer said.

"He was just dozing off," Migdalia Asevedo said. "A lady in the back of the bus was yelling at him for falling asleep."

Said passenger Angelo Serano: "We screamed and he realized (he was going to crash), but he already lost control."

Emergency crews worked Sunday night to lift the bus, which was rolled over on its side.

Waterbury Mayor Michael Jarjura said passengers were from Church of God Prophecy in Waterbury and two other nearby churches.

Twenty-three people were transported to Strong Memorial Hospital in nearby Rochester. They ranged in age from 11 months to 60 years old; seven were younger than 16.

Fischer said he believes three people were critically injured, including an 18-month-old child who suffered a blow to the chest. Most of the others were treated and released.

Passengers in the other vehicles suffered minor injuries.

"It made a royal mess," Trooper Gary Link said. "It's one of the worst accidents I've seen and I've been here 11 years."