A teenager who attacked two American tourists with a knife in Amsterdam’s central railway station was shot by Dutch police just nine seconds after the incident began.

The 19-year-old Afghan, identified only as Jawad S, is accused of stabbing the two 38-year-old foreigners in an unprovoked attack after arriving in the city last Friday from Germany.

The Amsterdam police commissioner, Pieter-Jaap Aalbersberg, told a Dutch TV program that the alleged attacker’s “abnormal behaviour” had been witnessed by a public transport police officer.

A teenage terror attack suspect was shot in just nine seconds after stabbing two US tourists in Amsterdam. (AP)

It is understood the officer, known as a “spotter’, had been trained to see potential criminals in crowds - such as pickpockets and potential terrorists – and acted as soon as Jawad allegedly attacked his first victim.

"There were two victims and that is very serious, but the number was kept to a minimum," the commissioner said.

"Within nine seconds it was over and the officers made the difference during one precise moment," he added, stressing that they had saved lives.”

Dutch police confirmed that 'spotter' authorities, who saw the 19-year-old Afghan man's 'abnormal behaviour', followed him and leaped into action when he began to allegedly attack the tourists. (EPA)

The two American victims were left seriously injured but were not in a critical condition after the alleged attack.

Meanwhile, the teenage suspect remains in hospital and police in Amsterdam said they are in "intensive contact" with their German counterparts on the case.

The accused had been seeking asylum there.

The two American tourists were left seriously injured and the alleged attacker is in hospital but will face police questioning. (AP)

German authorities also did a search of the suspect's house, where they found and seized data storage items that will be analysed.

"The initial investigation by police does not indicate that the victims were deliberately chosen. The investigation is in full swing with all scenarios being considered," the Amsterdam mayor's office said.

While prosecutors say he did not know the victims were US citizens, they have claimed the suspect believes that Islam is "insulted" in the Netherlands, and that drove him to carry out an attack.

It is believed the man is seeking asylum in Germany, and German authorities have now searched his property. (EPA)

"It is apparent from his statements that he believes that in the Netherlands, the Prophet Muhammad, the Quran, Islam and Allah are repeatedly insulted," prosecutors said in a statement this week.

The US embassy in Amsterdam has since also released a statement on behalf of the two victims, paying tribute to local police and saying they "cannot thank them enough for what they did to save their lives".

The victims also thanked an information kiosk attendant at the station for rushing to their aid, and nurses, a surgeon and American consular staff for their support since the attack.

Dutch police also said that a potential motive for the alleged attack may have been the man's belief that Islam is 'insulted' by the Dutch. (EPA)

"The victims and their families said they appreciate everyone's support, thoughts, and prayers. The families are focusing on both physical and emotional recovery,” the statement said.

They hope to return to living meaningful and productive lives in the United States.”