TAIPEI - Two pilots were injured after an AT-3 trainer plane of Taiwan's air force collided in mid-air Friday with another in southern Pingtung county, which could have been caused by human error, investigators said Saturday after examining the scene.

The two pilots parachuted to safety and suffered from fracture and other minor injuries, and the other two flew their plane safely back to the air base.

Investigators said the fuselage of the plane was smashed and burned out, with debris spreading in an extensive area. There were no casualties on the ground.

According to the island's air force sources, the aging AT-3 trainer planes have caused seven pilot deaths and nine injures over the past three decades, and the planes were grounded for inspection.