Firefighters, police and ambulances were at the scene, helping evacuate people and take the injured to hospitals.
Television and drone footage showed the trains head-to-head on an overpass in the Palermo neighborhood of the Argentine capital. The passenger train's first car derailed and was damaged in the collision.
Reuters reporters at the scene saw passengers being taken on stretchers to ambulances and helicopters waiting to transport the most seriously injured to city hospitals.
"Ninety ambulances were used on the scene, 90 passengers were transferred and attended to, of which 30 were referred with (the most serious categorization) code red," Alberto Crescenti, head of the local emergency medical care system SAME told Reuters at the scene.
State-run train operator Trenes Argentinos said the crash happened at 10:31 a.m. (1331 GMT) and an investigation into the cause of the accident would be opened.
"So far, as reported by the health authorities present at the scene, there are at least 60 people with injuries of varying severity," it said in a statement.
MP/PR