A passenger train crashed into a maintenance train in Buenos Aires on Friday, leaving at least 30 people hospitalized, two of whom were in serious condition, emergency officials said.

The SAME emergency service said that firefighters had evacuated everyone on the passenger train after the accident in the suburb of Palermo.

"There are no fatalities. Dogs have combed through the wagons. We assisted 90 passengers, 30 of whom were transferred to hospitals, two of them with head trauma who were evacuated by helicopter," said SAME official Alberto Crescenti, speaking at the scene.

The accident took place at 1030am local time, when the urban train crashed into a maintenance train that, for unknown reasons, was stopped on the tracks.

"For now there is not enough information about the mechanics of the accident," said Buenos Aires Mayor Jorge Macri, also on the scene.