Two people were killed when a small plane crashed into a highway outside Monterrey, the capital of the northern Mexican state of Nuevo Leon, while on a test flight, the emergency management office said.

Pilot Luis Correa and mechanic Ramiro Sarabiachi died in the accident.

The Piper aircraft went down Monday at kilometer 24 of the Monterrey-Nuevo Laredo highway, emergency management office spokesman Enrique Robles told Efe.

The plane had taken off from the Aeropuerto del Norte in Apodaca, a city in the northern section of the Monterrey metropolitan area.

The cause of the crash has not been determined.