One man is dead after a car travelling on a highway overpass in west Ottawa left the road and crashed onto another highway below in rush-hour traffic this morning.

The black four-door sedan had been heading north on the Highway 416 overpass at about 8:15 a.m. ET when it crashed onto the eastbound lanes of the Queensway near the Holly Acres exit.

A Ministry of Transportation spokesperson told CBC News in an email that "while the ramp had been plowed, the contractor had not yet fully completed snow removal work on the shoulder" of the overpass at the time of the crash.

Ontario Provincial Police identified the man as a 46-year-old from Ottawa.

Firefighters, OPP and paramedics work at the scene of a fatal crash on Highway 417 eastbound under the Highway 416 overpass on Wednesday morning. (CBC News)

Alberto Asencio was heading to the Ottawa airport to drop off his grandparents when the car flew above their vehicle.

"All of a sudden ... I just saw a big puff of snow. And that's not unusual, as normally plows will kind of plow [snow from the overpass] onto the 417 below," Asencio told the CBC's Ashley Burke.

"But this time it was a little different, because a car came overhead and landed in the far left lane, almost hitting three other cars in the process."

Asencio said most people on the highway stopped.

Highway 'came to a standstill'

"At the time, all you could really see was a black sedan upside down," he said. "Coincidentally, there was a Renfrew [County] paramedic right in front of me that had stopped also. The entire highway pretty much came to a standstill.

"I'm just glad that there weren't more injuries in the process."

Ottawa paramedics said they found a man inside the car. He was pronounced dead at the scene.

The crash did not cause any other injuries or collisions, paramedics added.

Mike Nolan, chief of the Renfrew County Paramedic Service, was driving on the 417 when a car came crashing down from the 416 ramp. 0:57

The stretch of Highway 416 had been salted prior to Wednesday morning's crash, a Ministry of Transportation spokesperson said in an email.

Highway 417 reopened to traffic late Wednesday morning but the Highway 416 ramp onto Highway 417 westbound remained closed until Wednesday afternoon.

The OPP announced shortly before 3 p.m. ET that all lanes had been reopened.

Police continue to investigate and anyone with information is asked to contact the OPP at 613-270-9171.