Ottawa - It truly was an unidentified flying object that darted across the night sky over the Ottawa River this week.

"There's nothing in the river for us to find in terms of an airplane or helicopter or something that went down (Monday) night," Ottawa police Const. Alain Boucher said Tuesday afternoon.

"We're still looking into what could have caused this. There's a number of reasons this could have happened. We'll be looking into that in the next couple of days."

Several residents, both in Ottawa and in Gatineau, Quebec, reported lights smashing into the water around 10 p.m. Monday, along with a thunderous boom.

The calls prompted police, firefighters, paramedics and a helicopter from CFB Trenton to scour the waters for a downed aircraft.

Problem was, there was no physical evidence pointing to a plane wreck: No debris, no oil slick and no indication from airspace authorities that something fell off the radar. There was also no report of a missing aircraft.

Still, searchers launched their boats on Tuesday morning looking for clues that could confirm witness accounts.

They found a few objects in the water, but nothing significant until around 1:30 p.m., when sonar discovered something bulky more than nine metres below the surface.

An underwater camera couldn't reach it and searchers called off the mission not knowing exactly what the object was.

"The size and the shape doesn't lead us to believe it's any piece of an airplane or fuselage or anything like that," Boucher said. "It could be a rock, it could be a bunch of logs stuck together, it's hard to say."

"No one has come forward with any kind of videos or anything like that at this time," Boucher said. "None of the people actually reported seeing a plane go down at the same time."

Source: Sun Media