Washington, Jul 18 (IANS): Four people were killed after the small planes they were travelling on collided in mid-air around noon at North Las Vegas Airport in the US state of Nevada.

"At this time, there are four reported fatalities. Accident is still under investigation," the City of North Las Vegas Fire Department tweeted.

Each aircraft had two people aboard, Xinhua news agency reported.

The US National Transportation Safety Board said in a tweet that it is investigating the tragedy that struck Las Vegas involving a Piper PA-46 and a Cessna 172N, both of which are single-engine fixed-wing small planes.

Preliminary information indicates that the Piper PA-46 was preparing to land when it collided with the Cessna 172. The Piper crashed into a field east of Runway 30-Right and the Cessna fell into a water retention pond, reported the ABC affiliate KTNV-TV, a local television station in Las Vegas, citing the US Federal Aviation Administration.