A head-on collision by two trains between Sloterdijk and the central station in Amsterdam has left over 100 people injured, many of them critically.

The accident that occurred at around 6:30 pm local time (16:30 GMT) disrupted train services between Amsterdam and The Hague and also to the Schiphol airport.

The Amsterdam mayor's office said 117 people were injured, while a police spokesman put the number of injured at 136 people. Many of the injured are in a critical condition with serious neck and bone injuries

"We assume many people were thrown around the train by the crash: against walls, seats and other people," police spokesman Ed Kraszewski told Amsterdam's AT5 news station.

"Everybody was screaming. A lot of people were injured. There was a lot of blood," CNN quoted Giovanni Laisina, a passenger whose head was knocked against a window, as saying.

"I was shocked in the beginning, but because I don't have any injures at all ... for me it's OK. It's a little bit surreal," Laisina added.

Video footage on local TV channels showed rescue personnel working to retrieve people from the trains and rushing them to hospitals.

Reuters quoted a woman at the scene telling broadcaster AT5: "We heard a loud bang. I went outside and saw people on the street in panic."

"We then saw what had happened. Quite quickly there were emergency services at the scene. It was managed well. Some people had head wounds, others were limping," she said, according to Reuters.

The running of the two trains on the same track in opposite directions has stunned the authorities. Police spokesman Ed Kraszewski told CNN that one of the trains might have ignored a red signal.

Amsterdam Mayor Eberhard van der Laan paid a visit to the hospital where some of the passengers are recuperating.

"There are many wounded, but luckily they got help quickly. All the attention and care go out to those people that are severely wounded. I hope that it will all end well," van der Laan said.